Class 8 – Page 6 – PSEB Solutions

PSEB 8th Class Science Solutions Chapter 8 Cell Structure and Functions

September 28, 2024September 27, 2024 by Prasanna

Punjab State Board PSEB 8th Class Science Book Solutions Chapter 8 Cell Structure and Functions Textbook Exercise Questions and Answers.

PSEB Solutions for Class 8 Science Chapter 8 Cell Structure and Functions

PSEB 8th Class Science Guide Cell Structure and Functions Textbook Questions and Answers

Answer These

Question 1.
Indicate whether the following statements are True [T] or False [F].
(a) Unicellular organisms have one-celled bodies.
Answer:
True

(b) Muscle cells are branched.
Answer:
False

(d) Amoeba has irregular shape.
Answer:
True

Question 2.
Make a sketch of the human nerve cell. What function do nerve cells perform ?
Answer:
PSEB 8th Class Science Solutions Chapter 8 Cell Structure and Functions 1
Functions of Nerve Cell:

It receives and transfers messages.
It control and co-ordinate the functioning of different parts of the body.

Question 3.
Write short notes on the following :
(a) Cytoplasm
(b) Nucleus of a cell.
Answer:
(a) Cytoplasm.
It is a jelly-like fluid present inside the cell membrane. Various cell organelles are present in it. It contains water, sugar, minerals, lipids proteins etc.

(b) Nucleus.
As true nucleus is present in all the eukaryotic cells except mammalian RBCs, sieve tube cells, tracheids and vessels. It is formed of four components:
(i) Nuclear Membrane.
It is a two-layered envelope around the nuclear sap. It is porous (with nuclear pores) and semi-permeable membrane. Outer membrane is studded with ribosomes. It regulates exchange of materials between nucleoplasm and cytoplasm.

(ii) Nucleoplasm.
It is a semifluid colloidal substance in which nucleoli and chromatin fibres are present. It acts as nuclear skeleton and forms spindle for the cell division.

(iii) Nucleolus.
It is dense, spherical, naked and darkly stained structure and it is site of formation and store house of RNA.
PSEB 8th Class Science Solutions Chapter 8 Cell Structure and Functions 2
(iv) Chromatin Fibres.
These are long, fine and darkly stained threads which collectively form nuclear reticulum. During prophase of mitosis and meiosis, these condense to form a specific number of rods, called chromosomes. These are embedded with genes which are chemically formed of DNA and act as units of heredity and variation. They also help in the synthesis of structural and enzymatic protein.

Question 4.
Which part of the cell contains organelles ?
Answer:
Cytoplasm contains organelles.

Question 5.
Make sketches of animal and plant cells. State three differences between them.
Or
State four differences between animal and plant cells.
Answer:
Animal cells differ from plant cells in the following definite ways :

Plant cells	Animal cells
1. Plant cells have cell wall made up of cellulose.	1. Animal cells have no such walls and no cellulose.
2. Plant cells have chloroplasts.	2. Animal cells do not possess the chloroplasts.
3. Plants cells have thin cytoplasm and large vacuole.	3. Animal cells have thick cytoplasm with no vacuole.
4. Centrosome absent.	4. Centrosome present.
5. Reserve food is in the form of starch.	5. Reserve food is in the form of glycogen and param sylum.

PSEB 8th Class Science Solutions Chapter 8 Cell Structure and Functions 3

Question 6.
State the difference between eukaryotes and prokaryotes.
Answer:
Eukaryotes.
These are the organisms whose cells contain well defined nucleus with a clear nuclear membrane. Examples are onion cells, cheek cells.

Prokaryotes.
These are the organisms whose cells have no definite nucleus i.e. without nuclear membrane. Examples are bacteria, blue green algae.

Question 7.
Where are chromosomes found in a cell ? State their function.
Answer:
Chromosomes are found in nucleus of a cell. Chromosomes carry genes and help in inheritance or transfer of characters from the parents to the offspring.

Question 8.
‘Cells are the basic structural units of living organisms’. Explain.
Answer:
As a building cannot be constructed without bricks. Similarly, a body of living organism has basic structural unit such as cell. Cells are of different size, shapes and group together to form organs, organ systems etc.

Question 9.
Explain why chloroplasts are found only in plant cells ?
Answer:
Chloroplast are green coloured plastids. They impart green colour to plants and only plants make use of green colour to synthesis food.

Question 10.
Complete the crossword with the help of clues given below.
Across
1. This is necessary for photosynthesis.
3. Term for component present in the cytoplasm.
6. The living substance in the cell.
8. Units of inheritance present on the chromosomes.

Down
1. Green plastids.
2. Formed by collection of tissues.
4. It separates the contents of the cell from the surrounding medium.
5. Empty structure in the cytoplasm.
7. A group of cells.
PSEB 8th Class Science Solutions Chapter 8 Cell Structure and Functions 4
Answer:

PSEB Solutions for Class 8 Science Cell Structure and Functions Important Questions and Answers

Multiple Choice Questions

Question 1.
A slide is given in the figure below. What does this show ?
PSEB 8th Class Science Solutions Chapter 8 Cell Structure and Functions 6
(a) Cork cells
(b) Onion membrane
(c) Unicellular organism
(d) Multicellular Organism.
Answer:
(b) Onion membrane.

Question 2.
What is the name of basic structural unit in living organism ?
(a) Tissue
(b) Organ of body
(c) Cell
(d) Molecule.
Answer:
(c) Cell.

Question 3.
Which out of the following cell-organ is found in plants only ?
(a) Mitochondria
(b) Chloroplast
(c) Cell membrane
(d) Nucleus
Answer:
(b) Chloroplast.

Question 4.
Which organism is not unicellular ?
(a) Bacteria
(b) Amoeba
(c) Paramecium
(d) Algae or mould
Answer:
(d) Algae or mould.

Question 5.
Which of the cell organelle synthesise protein ?
(a) Lysosome
(b) Chromosome
(c) Ribosome
(d) Centrosome
Answer:
(c) Ribosome.

Question 6.
Who discovered cell ?
(a) Robert Hook
(6) M.J. Schleiden
(c) Schwann
(d) Robert Brown
Answer:
(a) Robert Hook

Question 7.
Which cell organelle is called suicidal bag ?
(a) Ribosome
(b) Lysosome
(c) Chromosome
(d) Centrosome
Answer:
(b) Lysosome

Question 8.
Which out of the following is unicellular organism?
(a) Amoeba
(b) Paramecium
(c) Bacteria
(d) All of these.
Answer:
(d) All of these.

Question 9.
Which is the power-house of cell?
(a) Centrosome
(b) Chloroplast
(c) Mitochondria
(d) Ribosome.
Answer:
(c) Mitochondria.

Question 10.
Name a human cell which can change its shape.
(a) White blood cells
(b) Red blood cells
(c) Platelets
(d) Plasma
Answer:
(b) Red blood cells.

Question 11.
Which organ of the cell is found in plant cell only?
(a) Cell wall
(b) Chromosome
(e) Nucleus
(d) Cytoplasm
Answer:
(a) Cell wall.

Question 12.
Which is the longest cell of human body?
(a) Nerve cell
(b) Muscular cell
(c) Red blood cells ,
(d) White blood cells
Answer:
(a) Nerve cell.

Question 13.
Of what the cell wall is made?
(a) Fat
(b) Cellulose
(c) Protein.
(d) Mineral Salt.
Answer:
(b) Cellulose.

Very Short Answer Type Questions

Question 1.
Fill in the blanks.
1. The cell is the …………………. and functional unit of organism.
2. Cell wall is found in ……………….. cells.
3. Power house of the cell is ………………….
4. Amoeba and Paramecium consists of a single …………………
5. Plastids are present only in ……………….. cells.
Answer
1. structural
2. plant
3. mitochondrion
4. cell
5. plant.

Question 2.
Choose the correct answer.
1. Suicidal bags of cells are ?
(a) Lysosomes
(b) Chloroplast
(c) Mitochondria
(d) Ribosomes.
Answer:
(a) Lysosomes

2. Plant cells do not have:
(a) Cell wall
(b) Centrosomes
(c) Plastids
(d) Mitochondria.
Answer:
(b) Centrosomes.

Question 3.
What is structural and functional unit of life ?
Answer:
Cell.

Question 4.
What is the contribution of Robert Brown in cell biology ?
Answer:
He discovered nucleus in the cells of orchid.

Question 5.
Who proposed the cell theory ?
Answer:
M.J. Schleiden and Theodore Schwann.

Question 6.
Name the smallest and largest cell.
Answer:
Smallest cell – Mycoplasma.
Largest cell – Ostrich egg.

Question 7.
Name the smallest and largest cell of human body.
Answer:

Smallest cell – nephron.
Largest cell – neuron.

Question 8.
Who called the protoplasm as the physical basis of life ?
Answer:
Huxley.

Question 9.
Give the contribution of Rudolf Virchow in the field of biology.
Answer:
He stated “omnis cellula e cellula” which means new cells are formed by the growth and division of pre-existing cells.

Question 10.
What are two types of cells on the basis of nature of nucleus ?
Answer:
Prokaryotic and Eukaryotic cells.

Question 11.
What is nucleoid ?
Answer:
Nucleoid. It is incipient nucleus of prokaryotes like bacteria and blue-green algal cells and is without nuclear membrane.

Question 12.
What is contribution of Robert Hooke in the field of cell biology ?
Answer:
Robert Hooke discovered the cell.

Question 13.
What are the three functional regions of a cell ?
Answer:
Plasma membrane, cytoplasm, nucleus.

Question 14.
Give the primary function of plasma membrane.
Answer:
It regulates exchange of material between cytoplasm and extra-celluar fluid.

Question 15.
Name the smallest sized cell organelle.
Answer:
Ribosome.

Question 16.
Which cell organelle is called suicidal bag ?
Answer:
Lysosome.

Question 17.
Name the largest sized cell organelle.
Answer:
Plastids.

Question 18.
Which cell organelle is called cell centre ?
Answer:
Centrosome.

Question 19.
What are organs ?
Answer:
Organs. Various body parts of animals and plants are called organs.

Question 20.
Who coined the word ‘Cell’ ?
Answer:
Robert Hooke.

Question 21.
Why Robert Hooke coined the word cell ?
Answer:
Robert Hooke was excited when he observed spaces in a cork slice those appeared like honeycomb. He called these compartments as cells.

Question 22.
Name some organs of plants.
Answer:
Roots, stem, leaves, flower, fruit.

Question 23.
Write examples of unicellular organisms.
Answer:
Amoeba, Paramecium, Bacteria, etc.

Question 24.
What is size of the smallest cell ?
Answer:
0.1 micron (μm) i.e. ten thousandth part of a millimetre.

Question 25.
What is yellow yolk in the egg of a hen ?
Answer:
It represents single cell.

Question 26.
Write the size of largest cell observable with naked eyes.
Answer:
170 mm.

Question 27.
What are cell organelles ?
Answer:
The parts of a cell are called cell organelles.

Question 28.
What role does cell membrane play in a cell ?
Answer:
Cell membrane encloses a liquid substance known as protoplasm. It regulates the flow of substances both into the cell and out of it.

Question 29.
Name four major elements responsible for protoplasm.
Answer:
Carbon, Hydrogen, Oxygen, Nitrogen.

Question 30.
What is nucleoplasm ?
Answer:
Nucleoplasm. It is the liquid protoplasm in the nucleus.

Question 31.
Who controls the activities of a cell ?
Answer:
Nucleus.

Question 32.
What do chromosomes do ?
Answer:
Chromosomes help in inheritance or transfer of characters from the parents to next generation.

Question 33.
What are chloroplasts ?
Answer:
The green plastids in the plants are called chloroplasts.

Question 34.
What is the shape of mitochondria ?
Answer:
Rod-shaped or spherical.

Question 35.
Name the power house of a cell.
Answer:
Mitochondria.

Short Answer Type Questions

Question 1.
What is a cell ?
Answer:
Cell.
Just as the bricks are the units of all types of houses, the cells are the units or building blocks of living organisms. Animals and plants like ant, housefly, dog, elephant, sunflower, neem etc. consist of cells.

Question 2.
Write the names of cell organelles.
Answer:
Cell Organelles.
Cell organelles are living strictures of cytoplasm. These include : Endoplasmic reticulum, Golgi apparatus, mitochondria, ribosomes, lysosomes, peroxisomes, plastids, sphaerosomes, glyoxysomes, centrosome. microtubules, microfilaments, cilia and flagella.

Question 3.
What is the difference between the plasma membrane and cell wall ? Give the functions of each one.
Answer:

Characters	Plasmsa membrane	Cell Wall
1. Occurrence	Around the protoplasm of all the cells.	Outside the plasma membrane in plant cells, bacteria, blue-green algae, fungi etc.
2. Nature	Thin and selective permeable.	Thick and freely permeable.
3. Chemistry	Lipoproteinous and trilaminar.	Formed of cellulose hemicellulose, pectin, water, etc.
4. Function	Regulates the exchange of materials between cytoplasm and extracellular fluid.	It is protective and supportive in function. It provides definite shape and prevents evaporation of water.

Question 4.
Which cell organelle is called “suicidal bag” and why ?
Answer:
Lysosome is commonly called suicidal bag of cell. It is so as it contains hydrolytic enzymes which help in digestion of foreign food or bacteria (by heterophagy) ; or reserve food or certain cell organelles (by autophagy) ; or the whole cell after the cell death (by autolysis).

Question 5.
Which cell organelle is called “power house” of the cell ? Write about its function briefly.
Answer:
Mitochondrion is commonly called “power house” of the cell because it is site of oxidative breakdown of glucose in aerobic cell respiration to produce energy- rich ATP molecules. One mole of glucose, in aerobic respiration, produces 36 ATP molecules.

Question 6.
Define the following terms :
(a) Protoplasm
(b) Cytoplasm
(c) Nucleoplasm.
Answer:
(a) Protoplasm is the physical basis of life and lies inside the cell membrane. It includes both cytoplasm and nucleoplasm.

(b) Cytoplasm lies between the cell membrane and nucleus. It contains various types of cell-organelles and cell-inclusions. It undergoes cyclosis. It is the site of protein synthesis, glycolysis, etc.

(c) Nucleoplasm lies inside the nucleus and contains only nucleoli and chromatin fibres. It does not undergo cyclosis. It forms spindle during cell division.

Question 7.
Draw a labelled diagram of plant and animal cell.
Answer:
PSEB 8th Class Science Solutions Chapter 8 Cell Structure and Functions 7

Question 8.
Describe the variations in shape and size of cells.
Answer:
The cells are generally round or spherical in shape. However, there is lot of variations in shape of cells. These can be cuboidal and columnar. Some of the animal cells are long and branched as in nerve cells.

Question 9.
What are unicellular and multicellular organisms ?
Answer:
Unicellular Organisms. The organism whose body is made of only a single cell is called a unicellular organism, e.g. Amoeba, Paramecium, Chlamydomonas, Yeast, Euglena etc.
PSEB 8th Class Science Solutions Chapter 8 Cell Structure and Functions 8
Multicellular Organisms. The organisms whose body is made of many cells is called a multicellular organisms, e.g. Man, Hydra, Dog, Elephant etc.

Question 10.
WTiat are organs and organ systems ?
Answer:
Organ. A group of tissues which perform a definite function of the body is called an organ.
Organ System. A group of organs which do a big job is called an organ system.

Question 11.
Draw the diagrams of different kinds of cells.
Answer:

Question 12.
How was the first cell discovered?
Answer:
PSEB 8th Class Science Solutions Chapter 8 Cell Structure and Functions 10
Robert Hooke in 1665 observed slices of cork under a simple magnifying device. Cork is part of the bark of a tree. He took thin slices of cork and observed them under his microscope. He noticed partitioned boxes or compartments in the cork slice. These boxes appeared like a honey comb.

He also noticed that one box was separated from the other by a wall or partition. Hooke coined the term ‘cell’ for each box. Cell in Latin means ‘hollow space.’

Question 13.
Discuss about the various shapes of cells.
Answer:
PSEB 8th Class Science Solutions Chapter 8 Cell Structure and Functions 11
Generally cells are round, spherical or elongated. Some cells are long and pointed at both ends. They exhibit spindle shape. Cells sometimes are quite long and thread like. Some are branched like the nerve cell or neuron.

Question 14.
Differentiate between unicellular and multicellular organisms.
Answer:
Differences between unicellular and multicellular organisms.

Unicellular Organisms	Multicellular Organisms
1. These organisms are made of only one cell.	1. These organisms are made of many cells.
2. All functions of body are performed by only a single cell.	2. Each function of the body is performed by a group of special cells.
3. Cilia are found. Examples. Amoeba, Paramecium etc.	3. Cilia are not found. Examples. Almost all animals.

Long Answer Type Questions

Question 1.
Describe the structure of a typical cell in detail.
Answer:
Structure of cell
A cell is the basic unit of life. It is capable of performing all functions of life and to fulfil all the functions, cell is made up of different parts. Basically, a cell is formed of three parts:
1. Cell membrane or plasma membrane
2. Nucleus.
3. Cytoplasm.

The cytoplasm is surrounded by cell membrane and nucleus constitutes the protoplasm of a cell. The typical structure of plant and animal cells are shown ahead:

1. Cell Membrane.
It is a delicate, thin membrane. It is also called plasma membrane. It forms the outermost layer in animals but in plant cells an additional membrane is present. It is called cell membrane in animal’s cell and cell wall in plant’s cell. Cell membrane has following functions:
(i) It provides shape to the cell.
(ii) It allows the flow of some substances into the cell and out of the cell.
(iii) It acts as a barrier to protect internal parts.
PSEB 8th Class Science Solutions Chapter 8 Cell Structure and Functions 12

2. Nucleus.
The oval or spherical structure, which is the controlling centre of all activities of the cell is called nucleus. Nucleus is made up of following parts:
(i) Nuclear Membrane. It is the membrane having pores which separates contents of nucleus from cytoplasm.
(ii) Nucleoplasm. The fluid present in nucleus is called nucleoplasm.
(iii) Nucleolus. Small spherical body made up of nucleoprotein. RNA is also present in nucleus.
(iv) Chromatin Material. Several thread like structures forming a network are present in nucleoplasm. Chromatin material is in the form of chromosomes which carries genes on it.

The nucleus has following functions:
Chromatin material of nucleus transmits characters from one generation to other.
It contains informations for carrying out all basic functions.

3. Cytoplasm.
The jelly like fluid inside the membrane of cell is cytoplasm. All tiny structures performing different functions, are present in it. These are called organelles.

It also contains water, sugar, minerals, lipids, proteins etc. The various cell organelles present in cytoplasm are:
(i) Mitochondria. They are commonly called Tower house of the cell’ because they help in release of energy from food. They also store energy. Mitochondria (singular mitochondrion) are oval or rod shaped organelle bounded by two membranes.

(ii) Endoplasmic Reticulum. A complex network of membranes which are present either attached to nucleus or free from it are endoplasmic reticulum. Its network extends from nuclear membrane to cell membrane. It helps in protein synthesis and also in transport of various substances.

(iii) Plastids. These organelles are present only in plant cells. These are of three types:
(а) Chloroplasts. Green coloured plastids are chloroplasts. The green colour is due to the presence of pigment chlorophyll. They are commonly known as ‘Kitchen of the’ cell’ because chloroplasts are the site of photosynthesis i.e. process of making food.

(b) Leucoplasts. Colourless plastids are called leucoplasts. These are present in the roots and underground modified stems.

(iv) Golgi Bodies. These are membrane-bound, piles of many flattened sacs. In plants, Golgi bodies are known as dictyosomes. They are mainly secretory in function.

(v) Vacuoles. The fluid-filled organelles present in a cell are vacuoles. In-plant cells, vacuoles are few in number and larger in size whereas, in animals, they are more in number and smaller in size. They maintain the turgidity of plants cells. Vacuoles also serve as a waste deposit bin in which unwanted materials may be diverted.

(vi) Lysosomes. Small spherical bodies having a single membrane are lysosomes. They sacrifice their own selves to destroy and digest various materials. They are also called ‘suicidal bags’. Plant cells do not have lysosomes.

(vii) Ribosomes. These are small rounded bodies that are present free or attached with the endoplasmic reticulum. They perform the function of protein synthesis.

(viii) Centrosome. It is a rod-like structure. It occurs close to the nucleus and helps in cell division.

PSEB 8th Class Social Science Solutions Chapter 3 Minerals and Energy Resources

September 27, 2024September 26, 2024 by Bhagya

Punjab State Board PSEB 8th Class Social Science Book Solutions Geography Chapter 3 Minerals and Energy Resources Textbook Exercise Questions and Answers.

PSEB Solutions for Class 8 Social Science Geography Chapter 3 Minerals and Energy Resources

SST Guide for Class 8 PSEB Minerals and Energy Resources Textbook Questions and Answers

I. Answer the following questions in 1-15 words :

Question 1.
Write the definition of mineral resources.
Answer:
Minerals are natural substances that are made up of one or more elements. These are found in the interior of the earth. These have a definite chemical composition. These are identified by their physical and chemical qualities.

Question 2.
Where do iron-ore is found in India?
Answer:

Bihar: Singhbhum.
Orissa: Mayurbhanjh.
Chhattisgarh: Durg and Bastar.
Karnataka: Bellary, Dharwar, Kudremukh.

Question 3.
What are the uses of copper?
Answer:
Copper is used for making utensils, coins, electrical wires and electronics. Their sheets are also made.

Question 4.
Name the famous gold mines in India.
Answer:
In Karnataka, Kolar and Hutti.
In Andhra Pradesh: Ramgiri.

Question 5.
How should we use atomic minerals?
Answer:
Atomic minerals should be used carefully. These should be used for the development of the country and not for destruction and pollution.

Question 6.
What are the non-conventional sources of energy?
Answer:
Water power, solar energy, wind power, geothermal energy and tidal energy.

Question 7.
Name the four types of coal.
Answer:

Anthracite
Bituminous
Lignite
Peat.

Question 8.
What are multipurpose projects?
Answer:
The dams built mainly for power generation are called multi- purpose projects as these provide many benefits at the same time.

II. Answer the following questions in 50-60 words :

Question 1.
Which are the countries from where iron ore is mainly found? Write down the different types of iron ore :
Answer:
Countries: Russia and its neighbouring countries, Australia, Brazil, U.S.A. produce large quantities of iron ore. India produces 5% iron ore in the world.

Types of Iron ore :

Magnetite
Haematite
Limonite
Siderite.

Question 2.
Write down a note on the importance of Bauxite.
Answer:
Aluminium is extracted from Bauxite. It makes up about 8 per cent of the earth’s crust. It is light, strong and a very good conductor of electricity. It is largely used in various industries like transportation (aircraft, ship building, automobiles), chemical industries, electrical goods, machines, etc. It is used in making utensils, coins, furniture, sheets, packing material, photo-frames, pipes, etc. It is the basis of our telecommunication systems as it is used in radios, telegraphs, televisions and electrical wires. Due to its wide uses, it has been described as the ‘champion of metals’ or ‘the metal of the twentieth century’.

Question 3.
What is the importance of natural gas in our life and name the major areas in our country where it is found?
Answer:
Natural gas is produced in areas producing petroleum. When an oil well is dug, Natural gas is found in upper layers.

Use: It is used in homes for cooking, in vehicles and in industry.

Production: All the petroleum-producing countries produce Natural gas. The U.S.A. is the leading producer in the world. Russia, Middle East, Canada, Uzbekistan are other producers. Natural gas is produced in some parts of India. These include the Krishna-Godavari basin, Bay of Bengal-Orissa region and Barmer region of Rajasthan. Gulf of Cambay and Kutch region in Gujarat is a potential area. About 75% of the production of India comes from Bombay High.

Question 4.
Name the important factors which are favourable for the generation of Hydroelectricity?
Answer:
The development of water power (Hydro-electric power) depends upon the following factors:

Uneven relief. Mountainous areas provide quite good sites for the development of water power. Such areas provide rapids or falls.
Abundant rainfall. Fairly = heavy rainfall uniformly distributed throughout the year is necessary for water power development.
Presence of huge rivers and waterfalls. There should be some large rivers like Indus or Nile to provide large and regular supply of water.
Presence of lakes. The presence of lakes along the course of a river helps to regulate water flow naturally.
Nearness to market. The consuming areas should be near the power stations to avoid the loss during transmission.

III. Answer the following questions in about 125-130 words :

Question 1.
What are energy resources? What is their contribution towards the development of the country? Write in detail about any two energy resources.
Answer:
Coal: Coal is the prime source of energy. It is often called the ‘Mother of Industries’. It has been the basis of industrial revolution. Coal is used as a raw material in iron and steel, chemical industries. India ranks seventh in the world as regards coal reserves. The total proven coal reserves are nearly 214,000 million tonnes. These reserves will not last long. The major states known for coal reserves are Jharkhand, Bihar, Orissa, West Bengal, Chhattisgarh, M.P., Andhra Pradesh and Maharashtra. Coal production is 330 million tonnes (4% of world).

Distribution: India has two types of coalfields :
(a) Gondwana coalfields (98%)
(b) Tertiary coalfields (2%).

(a) Gondwana coalfields: These belong to the period of Gondwana age. Nearly 3/ 4th of coal deposits are found in Damodar valley (Damuda series). Godavari, Mahanadi, Son and Wardha valley have also coal deposits.

W. Bengal. West Bengal has the oldest coalfield of India at Raniganj. It covers an area of 1267 sq. km.
Jharkhand and Bihar. These two states produce 50% coal of India. The major coalfields of Jharia, Bokaro, Karanpura, Daltonganj are found in Damodar valley. Coking coal from this coalfield is supplied to steel centres of Jamshedpur, Asansol, Durgapur and Bokaro.
Chhattisgarh and Madhya Pradesh have Son valley coalfields of Suhagpur, Korba, Rampur, Tatapani, Singrauli.
Petroleum: In about 10 lakh sq. km oil-bearing rocks are found in India. The oil reserves in India are estimated to be about 4000 million tonnes.

The first oilfield in India was discovered in 1867 at Makum in Assam. At present the production is as below (334 lakh tonnes) :

Assam: In Assam oil is produced in Digboi, Moran, Naharkatiya and Sibsagar regions.
Gujarat: In Gujarat oil is produced in the Gulf of Cambay region at Kalol, Ankleshwar, Lunej, etc.
Maharashtra: Oil has struck in the off-shore region at Bombay High along the coast of Mumbai. It is the leading producer of crude oil in India. North Basin and South basin are the important oilfields.

The production of oil in India is increasing everywhere under the organization of Oil and Natural Gas Commission.

IV. Map Skill

Question 1.
Show one important area of minerals and energy resources on map of India
1. Iron ore
2. Manganese
3. Gold
4. Mica
5. Coal
6. Petroleum.
Answer:

V. Activity

Question 1.
Prepare a list of atleast ten minerals.
Answer:

S.No. Name of the minerals	Name of state of India in which mineral is found	Use of the mineral
1. Iron ore	Jharkhand	Iron steel industries
2. Manganese	Madhya Pradesh	Steelmaking
3. Gold	Karnataka	Jewellery
4. Copper	Jharkhand	Electrical industries
5. Mica	Bihar	Chemical Industries
6. Uranium	Jharkhand	Utensils
7. Bauxite	Andhra Pradesh	Chemical
8. Coal	Jharkhand	Power
9. Petroleum	Assam	Power
10. Hydroelectricity	Maharashtra	Power

PSEB 8th Class Social Science Guide Minerals and Energy Resources Important Questions and Answers

Multiple Choice Questions :

Question 1.
Which one of the following is not a type of mining?
(a) Open cast
(b) Shaft
(c) Drilling
(d) Shaft.
Answer:
(d) Shaft.

Question 2.
Which is the hardest mineral?
(a) Diamond
(b) Granite
(c) Basalt
(d) Gatbro.
Answer:
(a) Diamond.

Question 3.
Which is the first metal discovered by man?
(a) Copper
(b) Silver
(c) Gold
(d) Iron.
Answer:
(a) Copper.

Question 4.
Name the diamond which is rarest diamond.
(a) Green diamond
(b) White diamond
(c) Pink diamond
(d) Brown diamond.
Answer:
(a) Green diamond.

Question 5.
Which is a ferrous mineral?
(a) Bauxite
(b) Iron
(c) Mica
(d) Coal.
Answer:
(b) Iron.

Question 6.
What is the name of mining shown in the picture?

(a) Open Cast
(b) Shaft
(c) Drilling
(d) Shaft mining.
Answer:
(d) Shaft mining.

Question 7.
Which source of energy is the activity in the picture associated with?
Or
Seeing the picture tell the source to which it belongs.

(а) Hydroelectricity
(b) Solar energy
(c) Wind energy
(d) Nuclear (Atomic) energy.
Answer:
(a) Hydroelectricity.

Fill in the Blanks :

Question 1.
The __________ metals do not contain metals.
Answer:
Non-Metallic

Question 2.
Gondwana coalfields belong to the period of __________ age.
Answer:
Gondwana

Question 3.
Biogas is produced in __________ areas.
Answer:
Rural

Question 4.
Khetri is famous for __________
Answer:
Copper

Question 5.
In Gujarat oil is produced in the __________ region.
Answer:
Gulf of camboy.

True/False :

Question 1.
Energy generated by Tides is called Tidal energy.
Answer:
True

Question 2.
West Bengal has the oldest coalfield of India.
Answer:
True

Question 3.
Iron is a non-ferrous mineral.
Answer:
False

Question 4.
Jharia is famous for Atomic energy.
Answer:
False

Question 5.
Gold metal is used for decoration.
Answer:
True.

Very Short Answer Type Questions

Question 1.
Into how many categories can minerals be classified? Give two examples of each.
Answer:
Minerals are grouped into three categories :

Metallic Minerals. Iron ore, tin.
Non-metallic Minerals. Diamond, Gypsum.
Atomic Minerals. Uranium, Thorium.

Question 2.
Distinguish between Ferrous and Non-ferrous minerals.
Answer:

Ferrous minerals	Non-ferrous minerals
1. The metallic minerals which contain iron content are called ferrous minerals (Fe).	1. The minerals which do not contain iron (ferrous) content are called non-ferrous minerals (Nfe).
2. Iron, Manganese, Chromite, Cobalt, etc. are ferrous minerals.	2. Copper, Lead, Zinc, Aluminium are non-ferrous minerals.

Question 3.

What are the uses of Manganese?
Answer:

It is used for manufacturing bleaching powder.
It is used in insecticides.
It is used for making paints and batteries.

Question 4.
Where does India rank in the production of manganese in the world? Where is it found in India?
Answer:
India ranks second in world production of Manganese. In India the main producing areas are Karnataka, Orissa, Madhya Pradesh, Maharashtra, West Bengal and Goa.

Question 5.
What is Bronze? What is its use?
Answer:
It is a hard and strong product. Tin and copper are mixed to make it. It is used in making tools and weapons.

Question 6.
Where is copper found in the world ? Name the copper producing areas in India.
Answer:
USA, Russia, Chile, Zambia, Canada and Zaire are the main producers of copper. In India copper is found in Singhbhum (Jharkhand), Balaghat (Madhya Pradesh) and Jhunjhunu, Alwar (Rajasthan).

Question 7.
Which two states of India are large producer of Bauxite? Name two copper producing areas of these states.
Answer:
Jharkhand and Rajasthan are Bauxite producing states of India. Copper is mined at Singhbhum and Khetri.

Question 8.
What are the uses of Gold?
Answer:
Gold is a valuable metal :

It is used for making ornaments and articles for decoration.
It is used for gold plating, teeth covers and medicines.

Question 9.
What are the uses of copper?
Answer:
Copper is a soft and brown-coloured metal. It has been used by man for a very long time. It is mixed up with tin to be known as Bronze. It is used in the production of utensils, coins, electric wires.

Question 10.
Which minerals are used to produce atomic energy?
Answer:
Uranium, Thorium, Lithium and Zircon are used to produce atomic energy.

Question 11.
Why is petroleum called Rock oil?
Answer:
Petroleum or ‘mineral oil is called rock oil because it is formed in sedimentary rocks. It is called crude oil.

Question 12.
Which country is the largest producer of Gold in the world? And how much?
Answer:
South Africa is the largest producer of gold in the world. It produces about 70% gold of the world.

Question 13.
What is Mica? Why is it used in electrical goods industry?
Answer:
Mica is black or brown or white transparent material. It is a non-metallic .mineral. It is non-conductor of electricity. So it is used in electrical goods industry.

Question 14.
Describe the different methods of extracting minerals.
Answer:
Taking out minerals from rocks is called mining :

Open cast mining: Minerals at shallow depths are taken out by removing the surface layer.
Shaft Mining: Minerals at depth are taken out by making deep bores.
Drilling: Deep wells are bored to take out petroleum.
Quarrying: Minerals at surface are dug out.

Question 15.
Most industries are concentrated around coal mines.
Answer:
Most industries are concentrated around coal mines because coal is an important source of energy. It is key mineral and fuel for the industries. It is used as a power resource in many industries. Many industries use it as a raw material. So most industries are concentrated around coal mines.

Question 16.
Petroleum is referred to as “black gold”. Why?
Answer:
Nowadays petroleum is a major source of energy in the world. Many byproducts such as kerosene, fuel, lubricating oils etc. are obtained from it. Petrochemical products have become very useful. Petroleum is used in agro-industry, paints, perfumes, transport, etc. So it is rightly called the “black gold”.

Question 17.
Distinguish between conventional and non-conventional sources of energy.
Answer:

Conventional Sources	Non-conventional Sources
1. The sources of energy which have been used since a long time are called the conventional sources of energy. .	1. The sources of energy which have not been commonly used are called non conventional sources of energy
2. Wood, fuel, coal, petroleum gas and water power are conventional sources of energy.	2. Wind, tidal power, Geothermal energy, bio gas, solar energy are non conventional sources of energy.

Question 18.
Distinguish between
(i) Thermal power and Hydel power.
Answer:
Thermal Power and Hydel Power

Thermal Power	Hydel Power
1. It is expensive.	1. It is comparatively cheaper.
2. It is a limited resource.	2. It is an unlimited resource.
3. It creates problems of atmospheric pollution.	3. It is non polluted.
4. The electricity generated by coal or petroleum is called thermal power.	4. The electricity generated by running water is called hydel power.

(ii) Anthracite coal and Bituminous coal.
Answer:
Anthracite coal and Bituminous coal

Anthracite coal	Bituminous coal
1. It is the best quality of coal.	1. It is the low quality of coal.
2. It causes very less pollution.	2. It causes more pollution.
3. It gives more energy.	3. It gives less energy.
4. It is found only in J & K.	4. It is found in West Bengal, Orissa, Chhattisgarh and Jharkhand.

Question 19.
How should the natural resources be conserved?
Answer:
The natural resources should be used carefully in a planned manner. No resource should be wasted. These should be used so that the future generations can also use these.

Question 20.
Distinguish between Metallic and Non-metallic minerals.
Answer:

Metallic Minerals	Non-Metallic Minerals
1. Metals are malleable i.e., they can be beaten into sheets.	1. They are brittle in nature and cannot be beaten into sheets.
2. They are good conductors of heat and electricity.	2. They are bad conductors of heat and electricity.
3. All metals are solids.	3. They may be solids, liquids and gases.
4. For Example iron, copper.	4. For Example sand, diamonds.

Question 21.
‘Human civilisations are associated with discovery of minerals.’ Give example.
Answer:
Mining is an age-old activity. The use of minerals is marked with different stages of human civilisation. During 5000 B.C., copper age existed. During 3000 B.C., Bronze age and during 1400 B.C., iron age were developed.

Question 22.
What are the alternative sources of energy?
Answer:
There are other sources of energy as well. They include hydropower, geothermal, nuclear, solar and wind. These are also referred to as the alternative energy sources.

Question 23.
Many African countries have large potential of water resources but they have not used it to generate hydro-electricity.
Answer:
Large amount of capital is required for making dams on rivers, fixing machines and turbines and buying of transmission lines. So in spite of the water resources they are not used to generate hydro-electricity.

Question 24.
Name four main belts where iron ore is found.
Answer:
The four main iron ore belts are :

Orissa – Jharkhand belt
Durg – Bastar Chandarpur belt
Bellary – Chick Manglur belt
Maharashtra – Goa belt.

Question 25.
‘Mineral conservation can delay a crisis.’ Explain.
Answer:
Due to growing population, the use of minerals is increasing at an alarming rate. Minerals will not last long. We need to find substitutes, reduce consumption, recycle mineral resources. It can delay a mineral crisis.

Question 26.
Classify the following metals :
(i) Ferrous
Answer:
Ferrous: Iron and Manganese

(ii) Non-ferrous
Answer:
Non-ferrous: Copper and Lead

(iii) Light metal
Answer:
Light metal: Aluminium

(iv) Rare metals.
Answer:
Rare metals: Zirconium.

Question 27.
List three basic ways through which energy is-obtained.
Answer:
Energy is the capacity to do work. It can be obtained by :

Direct heating like fire, sun, etc.
Electricity
Stored energy in the form of a battery.

Question 28.
Describe the different types of coal.
Answer:

Peat: Peat is the first stage of coal development. It is dark brown in colour. It has about 35 per cent carbon content.
Lignite: Lignite is the next stage of coal formation, which has almost 50 per cent carbon.
Anthracite: Lignite becomes sub-bituminous, bituminous and eventually anthracite coal. Anthracite has more than 85 per cent carbon. It is the best quality of coal. It is very hard, compact, black in colour. It ignites slowly and bums with short blue flame.

Question 29.
Describe the formation of coal.
Answer:
Coal is a black or brown rock consisting mainly of carbon. Coal is formed by the decomposition of vegetation of last ages. Most of coal deposits were formed in carboniferous age about 300 million years ago.

Question 30.
Describe natural gas as a source of conventional energy.
Answer:

Natural gas is found with petroleum deposits.
It is released when crude oil is brought to the surface.
It is used as a domestic and industrial fuel.
Russia, Norway, UK and the Netherlands are the major producers of natural gas in the world.
Jaisalmer, Krishna-Godavari delta. Tripura and some areas off shore in Mumbai have natural gas resources in India.
Very few countries in the world have sufficient natural gas reserves of their own.

Question 31.
Describe solar energy.
Answer:
Solar Energy:

Sun provides heat and light energy every day.
Solar energy trapped from the sun is used in solar cells to produce electricity.
These cells are joined into solar pan&b to generate power for heating and lighting purpose.
The technology of utilising solar energy benefits tropical countries with abundant sunshine.
Solar energy is also used in solar heaters, solar cookers, solar dryers along with community lighting and traffic signals.

Question 32.
Explain wind energy.
Answer:

Wind is an inexhaustible source of energy.
Windmills have been used for grinding grain and lifting water since times immemorial.
At present high speed wind rotate the windmill which is connected to a generator to produce electricity.
Wind farms are clusters of wind mill. They are located in coastal regins and in mountains passes where strong and steady win blows.
Wind farms are found in Netherland, Germany, Denmark, UK, USA and Spain, ‘ They are known for wind energy production.

Question 33.
Give an account of nuclear power.
Answer:
Nuclear power:

Nuclear power is obtained frm energy stored in the nuclei of atoms of naturally occurring radioactive fuels like uranium and thorium.
These fuels undergo nuclear fission in nuclear reactors and emit power.
USA and Europe are the greatest producers of nuclear power.
In India: Rajasthan and Jharkhand have large deposits of uranium.
Thorium is found in large quantities in the monozite sands of Kerala.
Nuclear power stations in India are located in Kalpakkam (Tamil Nadu), Tarapur (Maharashtra), Ranapratap Sagar near Kota (Rajasthan), Narora (Uttar Pradesh) and Kaiga (Karnataka).

Question 34.
How is geothermal energy used?
Answer:
Geothermal Energy

Heat energy obtained from the earth is known as geothermal energy.
The temperature in the interior of the earth increases with increase in depth.
This heat energy comes on the surface in the form of hot springs. This heat energy is used to generate power.

Question 35.
Rajan lives in West Bengal. Which cereal crop should he sow in his field to maximise his profit?
Answer:
Rice.

Short Answer Type Questions

Question 1.
Describe the production of mica in world and in India.
Answer:
U.S.A., Russia, India, France, Argentina and South Korea are the main producers of Mica. India is the leading producer of mica in the world. But the production of mica is decreasing in India.

It is due to two factors :

The demand for mica is decreasing in the world.
The use of substitutes is increasing.

90% of the production of Mica in India comes from three states of Andhra Pradesh, Rajasthan and Jharkhand. Other producers are Bihar, Gujarat, Kerala, Madhya Pradesh, Chhattisgarh, Himachal Pradesh. The main districts are Nellore, Vishakhapatnam, Krishna (Andhra Pradesh), Jaipur, Udaipur, Bhilwara (Rajasthan), Gaya (Bihar), Hazaribagh (Jharkhand).

Question 2.
What is Nuclear Energy? Name the areas in India producing nuclear minerals.
Answer:
The energy generated by nuclear minerals is called nuclear energy. Uranium, Thorium, Lithium are nuclear minerals.

Areas of Production :

Uranium. Singhbhum, Hazaribagh (Jharkhand), Gaya (Bihar) Saharanpur (U.P.) and Udaipur (Rajasthan).
Thorium. Kerala, Jharkhand, Bihar, Rajasthan and Tamil Nadu.
Lithium. Jharkhand, Madhya Pradesh, Rajasthan, Chhattisgarh, Kerala.

Question 3.
Describe the importance of Natural Resources in our day to day life. Name the main areas of Natural Resources.
Answer:
Natural resources are free gifts of nature. These are very important for our lives. These are the index of a country’s progress and strength. These are called ‘the backbone of a country.

Areas of Natural Resources:

India’s 30% of the total area is covered with mountains. These have huge water and forest resources.
About 27% of the total area is covered with plateaus. These are storehouses of minerals.
About 43% of the total area is covered with plains. These have fertile soils and agriculture is well developed. These are ‘granaries’ of India.

Question 4.
Describe the Non-conventional sources of energy produced in India.
Answer:
Non-conventional sources of energy. Today non-conventional sources of energy include wind, tides, geothermal heat, biogas, farm and animal waste including human excreta.

All these sources are renewable or inexhaustible.
1. Wind energy: It can be used for generating electricity. It is estimated that wind alone can provide 2000 MW of electricity. The states of Gujarat, Tamil Nadu, Maharashtra and Orissa are better placed in regard to this energy. Areas with constant and high speed winds are suitable for the purpose.

2. Tidal energy: The Gulfs of Kutch and Cambay are ideally suited to develop electricity from the energy produced by high tides entering to narrow creeks.

3. Geo-thermal energy: India is not rich in this source. However, efforts are on to utilize natural energy of the hot springs at Manikaran in Himachal Pradesh.

4. Energy from urban waste: A pilot for demonstration purposes had already been set up in Delhi to treat solid municipal waste for conversion into energy. It produces nearly 4 MW energy every year. Sewage in cities is used for generating gas and electricity.

5. Biogas based power plants: Bagasse, farm wastes, rice husk are being used to produce electricity.

6. Farm animal and human wastes (Urja Gram): By using biomass, animal poultry waste and human excreta, gobar gas plants are being set up in villages.

7. Solar energy: Solar voltaic cells are used to generate solar energy.

Question 5.
Environmental aspects must be carefully looked into before building huge dams.
Answer:

Dams create an imbalance in the earth’s equilibrium.
Deforestation leads to environmental pollution.
People are displaced.
Cities/villages/towns are shifted causing untold hardships to people.
Silting of lakes a problem.

Fill in the blanks :

Question 1.
Russia is rich in __________ resource.
Answer:
Natural gas

Question 2.
Processing of digging out of minerals is known as __________
Answer:
quarrying

Question 3.
Biogas is produced in __________ areas.
Answer:
rural

Question 4.
India __________ in ferrous minerals.
Answer:
is rich

Question 5.
Australia is the largest producer of __________ in the world.
Answer:
bauxite

Question 6.
China and India have large __________ are deposits.
Answer:
iron.

Long Answer Type Questions

Question 1.
What is Hydel power? How is it generated? Describe its production in India and world.
Answer:
Hydel power is generated through falling water. Dams are built on rivers, the water is dropped from a height to rotate turbines. Due to friction, turbines generate electricity.

Production: Many countries have sufficient water resources. These countries produce large quantities of Hydel power. U.S.A., Russia, Japan, Germany, Canada, England, France, Italy, Poland, Brazil and India are the main producers. U.S.A. produces 31% water power of the world.

Hydel power in India. India produces sufficient Hydel power. But India’s share is only 1% in world production. Rivers and canals are the main sources.

Himalayan rivers
Peninsular rivers.

Ganga, Brahmaputra and tributaries are snow fed and perennial rivers. So these have large capacity to generate water power with 18% of total potential of India. But peninsular rivers are seasonal and depend upon rainfall. So their capacity is low.

Distribution: All the states, except, Goa produce Hydel power. Andhra Pradesh, Karnataka, Maharashtra, Punjab, Tamil Nadu, Orissa, Kerala states have large capacity. Uttarakhand and Himachal Pradesh are rich in Hydel power resources. We have to develop these resources.

Important: Projects,

Nagarjun Sagar Dam-Karnataka.
Ganga Hydro-electric system-U.P.
Tata Hydro-electric Grid-Maharashtra.
Hirakud Dam-Orissa.
Pandoh Project-Himachal Pradesh.
Bhakra-Nangal Project-Punjab.

Question 2.
Describe the economic importance of minerals. Explain the main types of minerals.
Answer:
Minerals. Mineral resources are of great use to man. Minerals have been called ‘The Gifts of Nature’. Mineral resources have been used since pre-historic times. Human civilisation has seen many ages like the stone age, copper age and iron age. Modern industrial and economic development depends upon the production and utilization of minerals.

Types of Minerals: There are 70 to 80 minerals found on the surface of the earth. These can be divided into three types :

Non-Metallic Minerals. These include salt, mica, limestone, graphite, potash, gypsum.
Metallic Minerals. These include iron, copper, aluminium, gold, silver. These can be melted into useful metals.
Fuel Minerals. These include coal, oil and natural gas. These are called sources of power.

Importance of Minerals :

Industries. Minerals form the basis of heavy industries like iron and steel. Minerals are called ‘vitamins’ of industry.
Machinery. Minerals provide machinery for modern manufacturing.
Transport. Minerals are used in the making of different means of transportation.
Sources of Energy. Minerals provide energy to modern industries.

Question 3.
Describe the production of Petroleum in India.
Answer:
Production. In about 10 lakh sq. km. oil-bearing rocks are found in India. The oil reserves in India are estimated to be 50 crore metric tons.
The first oilfield in India was discovered in 1867 at Makum in Assam. At present the production is as under:

Assam: In Assam, oil is produced in Digboi, Moran, Naharkatiya, and Sibsagar regions.
Gujarat: In Gujarat, oil is produced in the Gulf of Cambay region at Kalol, Ankleshwar, Lunej, etc.
Maharashtra: Oil has struck in the offshore region at Mumbai High along the coast of Mumbai. It is the leading producer of crude oil in India. North Basin and South Basin and Albet islands are the important oil fields.
The production of oil in India is increasing everywhere under the organization of the Oil and Natural Gas Commission. The production of oil in India was estimated to be about 210 lakh tonnes in 2001.

PSEB 8th Class Science Solutions Chapter 3 Synthetic Fibres and Plastics

September 27, 2024September 26, 2024 by Prasanna

Punjab State Board PSEB 8th Class Science Book Solutions Chapter 3 Synthetic Fibres and Plastics Textbook Exercise Questions and Answers.

PSEB Solutions for Class 8 Science Chapter 3 Synthetic Fibres and Plastics

PSEB 8th Class Science Guide Synthetic Fibres and Plastics Textbook Questions and Answers

Exercises

Question 1.
Explain why some fibres are called synthetic.
Answer:
Some fibres are called synthetic fibres because they are not obtained from natural sources. They are made by human beings. The raw materials used for preparing synthetic fibres are petrochemicals, which in turn are produced from fossil fuel, petroleum.

Question 2.
Mark (✓) the correct answer.
Rayon is different from synthetic fibres because
(a) it has a silk-like appearance
(b) it is obtained from wood pulp
(c) its fibres can also be woven like those of natural fibres.
Answer:
(b) It is obtained from wood pulp.

Question 3.
Fill in the blanks with appropriate words.
(а) Synthetic fibres are also called …………… or ……………….. fibres.
(b) Synthetic fibres are synthesised from raw material called ………………. .
(c) Like synthetic fibres, plastic is also a ………………… .
Answer:
(a) Man made, artificial
(b) Petrochemicals
(c) Synthetic.

Question 4.
Give examples which indicate that nylon fibres are very strong.
Answer:
Parachutes, ropes for climbing, tents made of nylon.

Question 5.
Explain why plastic containers are favoured for storing food.
Answer:
Advantages of using plastic containers for storing food:

They do not react with food, air and water.
They are strong and light in weight.
They can have different sizes, shapes and colours.

Question 6.
Explain the difference between thermoplastic and thermosetting plastics.
Answer:
Differences between the Thermoplastics and Thermosetting Plastics

Thermoplastics	Thermosetting plastics
1. It can bend easily.	1. It cannot bend but breaks.
2. On heating, it gets deformed.	2. Heating has no affect on it.
3. It can be used again and again.	3. It cannot be reused.
4. It can be moulded into various shapes on heating. Examples : Polythene, PVC.	4. It can be moulded only once, on heating. Examples : Bakelite, Melamine.

Question 7.
Explain why the following are made of thermosetting plastics.
(а) Saucepan handles
(b) Electric plugs/switches/plug boards
Answer:
(a) Saucepan handles are made of thermosetting plastics because plastic is bad conductor of electricity, fire resistant and heat tolerant.

(b) Electric plugs/switches/plugboards are made of thermosetting plastics because this plastic is bad conductor of electricity and durable.

Question 8.
Categorise the materials of the following products into ‘can be recycled’ and ‘cannot be recycled’.
Telephone instruments, plastic toys, cooker handles, carry bags, ball point pens, plastic, bowls, plastic covering on electric wires, plastic chairs, electrical switches.
Answer:
Can be recycled. Plastic toys, carrybags, ball point pens, plastic bowls, plastic chairs, plastic covering on electric wires.
Cannot be recycled. Telephone instruments, cooker handles, electrical switches.

Question 9.
Rana wants to buy shirts for summer. Should he buy cotton shirts or shirts made from synthetic material ? Advise Rana, giving your reason.
Answer:
Rana should buy cotton shirts.
Preference of cotton clothes to synthetic materials in summers.

Cotton clothes are porous while synthetic materials are non-porous or air resistant.
Cotton clothes soak sweat and give a dry feeling while synthetic clothes have little water absorbing property.

Question 10.
Give examples to show that plastics are non-corrosive in nature.
Answer:
Plastics are non-corrosive in nature. Plastics do not react with air, water etc. so, they do not get corroded.
For example –

Different chemicals are stored in plastic bottles.
Water is kept into plastic bottles.
Pickles and food items are stored in plastic containers.

Question 11.
Should the handles and bristles of a toothbrush be made of the same material ? Explain your answer.
Answer:
No, different materials should be used for making handles and bristles of toothbrush because bristles help in cleaning teeth and handle is just for support. Bristles must be soft and delicate and powerful while handle should be hard and rigid.

Question 12.
‘Avoid plastics as far as possible’. Comment on this advice.
Answer:
Plastics are not environment friendly. They release poisonous gases on burning. They are non-biodegradable, so pollute soil or water in which they are dumped. Therefore, use of plastic should be avoided as far as possible.

Question 13.
Match the terms of Column A correctly with the phrases given in Column B.

Column A	Column B
(i) Polyester	(a) Prepared by using wood pulp
(ii) Teflon	(b) Used for making parachutes and stockings
(iii) Rayon	(c) Used to make non-stick cookwares
(iv) Nylon	(d) Fabrics do not wrinkle easily

Answer:

Column A	Column B
(i) Polyester	(d) Fabrics do not wrinkle easily
(ii) Teflon	(c) Used to make non-stick cookwares
(iii) Rayon	(a) Prepared by using wood pulp
(iv) Nylon	(b) Used for making parachutes and stockings

Question 14.
‘Manufacturing synthetic fibres is actually helping conservation of forests’. Comment.
Answer:
Natural fibres are obtained from natural resources i.e. natural plants. But synthetic fibres are obtained from other materials. So, synthetic fibres are not dependent on natural vegetation or crops grown in the field. Thus manufacturing synthetic fibres actually helps conservation of forests.

Question 15.
Describe an activity to show that thermoplastic is poor conductor of electricity.
Answer:
PSEB 8th Class Science Solutions Chapter 3 Synthetic Fibres and Plastics 1
Activity.
Take a few samples of thermoplastic such like polythene, PVC, Nylon, Polystyrene etc.
Now set up the circuit as shown in fig. and insert a piece of Nylon between the two terminals A and B of copper wire. If bulb starts glowing then it is good conductor otherwise it is a bad conductor. Repeat the experiment using different samples of thermoplastics.
In each case, bulb would not glow indicating that thermoplastics are bad conductor of electricity.

PSEB Solutions for Class 8 Science Synthetic Fibres and Plastics Important Questions and Answers

Multiple Choice Questions

Question 1.
In the following diagram, a boy is seen using rope for going up a rock. Tell rope made of which material is most suitable for this purpose ?
PSEB 8th Class Science Solutions Chapter 3 Synthetic Fibres and Plastics 2
(a) Cotton
(b) Wood
(c) Nylon
(d) None of these.
Answer:
(c) Nylon.

Question 2.
Which of the following is called artificial silk ?
(a) Rubber
(b) Teflon
(c) Rayon
(d) Polythene.
Answer:
(c) Rayon.

Question 3.
…………… is used for making polyester clothes.
(a) P.E.T.
(b) Acrvline
(c) Terrylene
(d) None of these.
Answer:
(c) Terrylene.

Question 4.
Today while studying in the class Nisha came to know that there is such a type of plastic which melts when heated. Name this plastic. (From Board M.Q.P.)
(a) Plastic
(b) Thermoplastic
(c) Acrylic
(d) All of the above.
Answer:
(b) Thermoplastic.

Question 5.
Which out of the following is natural fibre ?
(a) Rayon
(b) Terylene
(c) Wool
(cl) Nylon.
Answer:
(c) Wool.

Question 6.
Which out of the following fibres is made by man ?
(a) Cotton
(b) Wool
(c) Rayon
(d) Silk.
Answer:
(c) Rayon.

Question 7.
Which out of the following is biodegradable ?
(a) Metal
(b) Plastic
(c) Paper
(d) All of these.
Answer:
(c) Paper.

Question 8.
Which of the following material is used to make ropes ?
(a) Cotton
(b) Wool
(c) Nylon
(d) None of the above.
Answer:
(c) Nylon.

Question 9.
Which type of thermoplastic is used to make switches, which is poor conductor of heat and electricity ?
(a) Nylon
(b) Backelite
(c) Melamine
(d) Polythene
Answer:
(b) Backelite.

Question 10.
Which out of the following is thermoplastic ?
(a) Nylon
(b) Polythene
(c) Acrylic
(d) Backelite
Answer:
(d) Backelite.

Question 11.
Synthetic fibres are made from small units called:
(a) Cell
(b) Molecules
(c) Polymer
(d) None of the above.
Answer:
(c) Polymer.

Question 12.
Sericulture is the bringing up of which creature ?
(a) Sheep
(b) Goat
(c) Hare
(d) Silk worm
Answer:
(d) Silk worm

Question 13.
Natural Polymer is:
(a) Rayon
(b) Cotton
(c) Nylon
(d) Polyster
Answer:
(b) Cotton.

Very Short Answer Type Questions

Question 1.
Name few natural fibres.
Answer:
Cotton, wool, silk.

Question 2.
Name a natural polymer.
Answer:
Cellulose.

Question 3.
Name a fibre which is silk like but man made.
Answer:
Rayon.

Question 4.
Which fibre is obtained from woodpulp ?
Answer:
Rayon.

Question 5.
In which year, Nylon was made ?
Answer:
In 1931.

Question 6.
Which fibre was made from coal, air and water ?
Answer:
Nylon

Question 7.
Of which fibre, parachutes and tents are made of ?
Answer:
Nylon

Question 8.
What is PET ?
Answer:
PET. It is a form of Polyester.

Question 9.
Why do parachutes and ropes for climbing rocks are made of Nylon ?
Answer:
Due to its strength.

Question 10.
Give few characteristics of plastics.
Answer:
Plastics can be recycled, reused, coloured, melted, rolled into sheets or made into wires.

Question 11.
What are Polythene and PVC ?
Answer:
Thermoplastics.

Question 12.
Bakelite is an example of which type of plastic ?
Answer:
Thermosetting plastic.

Question 13.
Where is Teflon used ?
Answer:
For making kitchen cookware and tape sealing.

Question 14.
Which of these fibres is costly-wool, rayon ?
Answer:
Wool.

Question 15.
Why does hot water deform plastic bottles ?
Answer:
Because they are made of thermoplastic, which melts on heating.

Question 16.
Which thermosetting material is versatile, heat resistant and fireproof ?
Answer:
Melamine.

Question 17.
Why is plastic used in cars, aircrafts etc. instead of metals ?
Answer:
Because it is lighter than metals.

Question 18.
Why are plastic containers convenient to use ?
Answer:
Plastic containers are light, cheap, strong and can be handled easily.

Question 19.
Which synthetic fibre resembles wool ?
Answer:
Acrylic.

Question 20.
Give two reasons for prefering synthetic fibres over natural fibres.
Answer:

Durability and
affordability.

Question 21.
Give one disadvantage of synthetic fibres.
Answer:
They melt on heating.

Question 22.
Which substances are non-biodegradable ?
Answer:
Non-biodegradable substances: Those substances which cannot be decomposed by bacteria are called non-biodegradable substances.

Question 23.
Which material or thing is responsible for choking drains and death of herbivores ?
Answer:
Polythene bags.

Question 24.
What is 4R principle ?
Answer:

Reduce,
Reuse,
Recycle and
Recover.

Question 25.
Plastics are non-biodegradable. Are they environment friendly or environment non-friendly ?
Answer:
Environment non-friendly.

Short Answer Type Questions

Question 1.
What are polymers ? Give an example of natural polymer. Are polymers found in nature ?
Answer:
Polymer.
A Polymer is a long chain consisting of lakhs of small units (molecules). It is made by combining together small molecules of chemical substances. Cellulose is natural polymer.

Polymers are found in nature. As for example, cotton is a natural fibre which in fact is cellulose. Cellulose is made up of large units of glucose. Similarly, wood pulp is cellulose from which rayon is manufactured. Therefore, rayon also a polymer.

Question 2.
What are synthetic fibres ?
Answer:
Synthetic Fibres.
The fibres other than natural fibres which are made by human beings are called synthetic fibres.
These are made of very large units which in turn are made up of similar small units.

Question 3.
Give few examples of synthetic fibres.
Answer:
Rayon, Nylon, Polyester, Plastic, Acrylic, Terylene etc. are synthetic fibres.

Question 4.
Give uses of Rayon and Nylon.
Answer:
Rayon is used to make clothes, bedsheets and carpets.
Nylon is used to make clothes, socks, ropes, tents, tooth brushes, belts, sleeping bags, curtains, parachutes etc.

Question 5.
List the characteristics of synthetic fibres which make them popular dress material.
Answer:
Characteristics of Synthetic Fibres:
Synthetic fibres possess the following unique characteristics:

They are durable.
They are less expensive.
They dry up quickly.
They are readily available.
They are easy to maintain.
It is easy to wash and does not wrinkle.
These characteristics make them popular dress material.

Question 6.
What happens when different synthetic fibres like Nylon, Polyester and Acrylic burn in air ?
Answer:
On burning the different fabrics, the following results are obtained :

1. Nylon	Burns with difficulty, fabric shrinks from flame, forming hard beads, smells of burning hair.
2. Polyester	Same as nylon, produces a black smoke on burning.
3. Acrylic	Shrinks from flame forming a black bead and a sooty flame.

Question 7.
Why plastic material like polythene is preferred over natural materials ?
Answer:
Advantages of Plastic material over Natural Material. Following are some advantages of plastic material (polythene etc.) over natural materials:

It is cheaper and can be made on a large scale.
It is light weight and can be easily transported.
It is unbreakable, corrosion free, tough and flexible.
It can be easily moulded.

Question 8.
Give uses of polythene.
Answer:
Uses of Polythene.
Polythene sheets are used for packing, satchels are used for packaging milk, polythene containers and pipes are used for storing and transporting water, oil and other materials. Polythene is also used as a water-proofing material.

Question 9.
Give some uses of PVC.
Answer:
Uses of PVC. PVC is used to make bottles, floor coverings, rain coats, soles of shoes, sandals and leather like materials.

Question 10.
What is blended fabric ? Why is it more comfortable to wear them than fabrics from pure synthetic fibres ?
Answer:
Blended Fabric (Polycot and Polywool).
It is a mixture of synthetic (man-made) and natural fibres such as terrycot (polyester and cotton fibres), terrywool etc. Pure synthetic fibres do not absorb sweat so well, so they stick to the body in hot weather. Some synthetic fibres catch fire very easily. To overcome this defect, synthetic fibres are mixed with natural fibres to make blended fabrics.

Question 11.
What are biodegradable and non-biodegradable substances ?
Answer:
Biodegradable Substances.
Substances which are decomposed by microbes (bacteria) are known as biodegradable substances. Bodies of dead animals, human excreta and many other substances are decomposed into simpler compounds or elements by bacteria. Such substances are biodegradable substances.

Non-biodegradable substancs.
Those substances which are not decomposed into simpler compounds by naturalprocessesor or bacteria are known as non-biodegradable substances.

Question 12.
What are natural and synthetic polymers ?
Answer:
1. Natural Polymers. The polymers which occur in nature and are obtained from plants and animals e.g. rubber, starch, cellulose, proteins etc. are called natural polymers.

2. Synthetic Polymers. The polymers which do not occur in nature and have been synthesised in laboratory are called synthetic polymers. These are also called manmade polymers e.g. polythene, poly-vinyl chloride, teflon, bakelite etc.

Question 13.
Suggest some ways to reduce the use of plastic materials.
Answer:
Plastic is non-biodegradable and is therefore, not environment friendly. The best way to reduce its use is to follow the 4R principle, which is as follows:

Reduce – use less
Reuse – use again
Recycle – cycle again
Recover – get again

Question 14.
Which way the plastic/polythene bags and wrappers thrown carelessly be harmful to animals ?
Answer:
The plastic/polythene bags and wrappers thrown carelessly after use are swallowed by stray animals. These plastic made materials are non-biodegradable either choke the respiratory canal of the animals or forms a lining in their stomach resulting in the cause of their death.

Question 15.
In which ways excessive use of plastic materials is harmful for environment and society ?
Answer:
Plastic is harmful for environment and the man in the following ways:

Since Plastic is synthesised from petrochemicals so its excessive use would lead to exhaustion of non-renewable petrochemical the reserve of which is limited.
Plastic is non-biodegradable and clogs the drains and sewage system if thrown carelessly after use which usually happens.
Plastic does not burn completely and releases lots of poisonous fumes in the atmosphere causing air pollution.
Sometimes carelessly thrown plastic/polybag are swallowed by animals resulting in their death.

Question 16.
Why it is not advised to wear polyester clothes while working in a kitchen ?
Answer:
Polyester is a synthetic fibre. It easily catches fire and melts so that it sticks to the body causing harmful and painful burns. That is why women are advised not to wear polyester clothes while working in kitchen.

Question 17.
As a sensible and responsible citizen what measures would you adopt in your individual capacity to keep public places free from plastic ?
Answer:

I would not throw plastic carry bags in water bodies and on the road after use.
While going to market for shopping I would take cotton or jute bag with me or I would insist on the shopkeeper to give me paper bag.
I would use steel lunch box instead of one made from plastic.

Question 18.
Four students planned to climb the top of mountain. They have selected the rope according to the table shown below. Which student has selected the correct rope and why ?

Name of the Students	Rope
Inderjeet	Cotton
Gopal	Silk
Saloni	Nylon
Karamjit	Wool

Answer:
Saloni has choosen the correct rope because the rope of nylon is stronger than silk and wool.

Long Answer Type Questions

Question 1.
Give uses of the following:
(a) Polyester fibres
(b) Teflon
(c) Polythene
(d) Polypropylene
Answer:
(a) Uses of Polyester Fibres:

Polyester fibres are used in textile industry for making a variety of clothes, such as sarees, dress materials, curtain clothes, etc.
Polyester fibres mixed with natural fibres are used for making blended textiles such as terrycot (mixed with cotton), terry wool (mixed with wool).
It is used for making sails of sail boats.
It is used for making water hoses for fire fighting operations.

(b) Uses of Teflon:

It is used for coating inside of non-stick cooking utensils.
It is used in the manufacture of seals and gaskets.

It is used in the manufacture of bags, toys and pipes.
It is used for covering electric cables because it is a good electrical insulator.

(d) Uses of Polypropylene:

It is used to prepare seat covers.
It is used for making ropes, fishing nets etc.

Question 2.
State four important properties and uses of nylon fibres.
Answer:
Properties of Nylon Fibres:

Nylon fibres are very strong.
Nylon fibres absorb very less water. Therefore, these can be dried rapidly.
Nylon is wrinkle resistant and keep permanent creases.
Nylon fibres have high wear and tear resistance and therefore, have longer life.

Use of Nylon:

Nylon is used for a large number of purposes where high strength fibres are required.
Nylon is used for making parachute fabrics, fishing nets, tyrecord, ropes, stockings (socks) and other textiles.
Nylon is mixed with wool to make long-lasting fabrics.

Question 3.
Give the properties common to Nylon and Polyester fibres.
Answer:
Properties of Nylon and Polyester Fibres:

Nylon and polyester fibres are very strong threads in comparison to silk, cotton, and wool.
Both the threads have excellent resistance to wrinkles.
Both the threads absorb very little water, so they dry out quickly.
They have the high abrasion resistance and are not attacked by moths.
Ordinary chemicals have no effect on them.
They are lightweight and fine in texture.
They are insoluble in common solvents.

Question 4.
What is plastic? What are its different types? Give properties of plastics which render them as a material of choice. Also, give its uses.
Answer:
Plastic. It is a polymer like synthetic fibre.
Example. Polythene

Types of Plastic. All plastics do not have the same arrangement of units. There are two types of plastics: One has a linear arrangement of units and the other has a cross-linked arrangement of units.

Properties of Plastics:

Plastic is not attacked by air and water. That is they are non-reactive and non¬corrosive.
Plastic is light, strong, and durable.
Some plastics can be easily deformed on heating and some others do not soften on heating.
Plastics are poor conductors of heat and electricity.

Uses of Plastics:

In Health Care Industry. Plastics find extensive use in the Health care industry for packaging tablets, threads used for stitching wounds syringes, doctor’s gloves, and many other instruments.
In Kitchen Cookwares. Plastic is used for making special cookwares to be used in micro-ovens which can withstand high temperatures.
In making non-stick cookwares on which Teflon, a kind of plastic is used, oil and water do not stick.
Fire Proof Plastics. Melamine plastic is used for coating the uniforms of firemen. This makes the uniform flame resistant.

PSEB 8th Class Social Science Solutions Chapter 2 Natural Resources

September 26, 2024September 25, 2024 by Bhagya

Punjab State Board PSEB 8th Class Social Science Book Solutions Geography Chapter 2 Natural Resources Textbook Exercise Questions and Answers.

PSEB Solutions for Class 8 Social Science Geography Chapter 2 Natural Resources

SST Guide for Class 8 PSEB Natural Resources Textbook Questions and Answers

I. Answer the following questions in 1-15 words:

Question 1.
Into which relief features can the land be divided?
Answer:
Mountains, plateaus, and plains.

Question 2.
What is the importance of plains?
Answer:
Plains support agriculture and dense population. These meet human needs. Plains are suitable for the development of vegetation and crops.

Question 3.
What are the factors that affect the formation of soils?
Answer:
Parent rocks, climate, plants and animals.

Question 4.
How many types of soils are found in India? Write the names of these types.
Answer:

Alluvial soils
Black soils
Red soils
Laterite soils
Forest and Mountain soils
Desert soils.

Question 5.
What type of crops can be grown on Black soil?
Answer:
Cotton, wheat, jowar, flax, tobacco, sun flower, crops are grown in Black soils. Rice and sugarcane are grown with the help of irrigation.

Question 6.
Write the names of main sources of water.
Answer:

Rainfall
Rivers and streams
Canals
Tanks
Groundwater.

Question 7.
What is given by the natural vegetation to man?
Answer:

Timber (wood) which is used for buildings.
Fruit, medicines and other products.

Question 8.
Name the types of forests found in India.
Answer:

Evergreen forests
Deciduous forests
Desert forests
Mountain forests
Delta forests.

Question 9.
What are migratory birds and where do they come from?
Answer:
In cold season birds migrate to India. These are called migratory birds. These come from Mosay Siberia and China.

II. Answer the following questions in 50-60 words :

Question 1.
Write about the land use in India.
Answer:
Land use pattern. India has a total geographical area of 32.8 crore hectares. Main characteristics of land use are given below:

Net Sown Area. About 46% of total land (77 crore hectares) is net sown area. This vast area shows the importance of agriculture in India as crops are grown in it
Fallow land. About 8% land (2.2 crore hectares) is left as fallow land and is cultivated after two or three years.
Forests. About 22.2% of land is (6.6 crore hectares) under forests. It should be 33%. Afforestation be done and’ deforestation be banned.
Plantation crops. About 1% land is under plantation crops like tea, coffee, etc.
Other uses. Land under permanent grassland, cultivable waste and not available for cultivation amounts to about 5 crore hectares.
Area under forests is increasing. Fallow land has been reduced in area. Net sown area under doubled cropped area is also increasing.

Question 2.
After mentioning the types of soil write the importance of alluvial soil.
Answer:
There are six types of soils in India :

Alluvial soils
Black soils
Red soils
Laterite soils
Forest and Mountain soils
Desert soils.

Alluvial Soils: These are made up of fine particles. These are clay soils and fertile soils. Therefore, the alluvial plains are very useful for agriculture. For example, the Indus- Ganga-Brahmputra plain of India. It has two types-Khadar and Bangar soils.

Question 3.
How is the soil resource being conserved?
Answer:
Soil Conservation. Soil is a very fundamental natural resource. Soil formation is a slow process, but it is easily lost by soil erosion. Sound farming practices and measures be adopted to conserve, protect, renew and maintain soil fertility.

These methods constitute soil conservation.

Afforestation: Afforestation and reforestation is needed to hold the soil.
Controlled grazing: The number of cattle to be grazed on slopes should be according to the carrying capacity of the pastures.
Terraced agriculture: Slopes must be cut into a series of terraces (fields) for cultivation so as to slow down the flow of rain water.
River dams: River dams are built in the upper course of rivers to control floods and check soil erosion.
Crop rotation: Crop rotation system be applied and the land should be allowed fallow for some time. Soil fertility can be maintained in this way.

Question 4.
Give the importance of rivers and canals.
Answer:
India has a total of 1869 billion cubic metre water resources. Out of this, only 660 billion cubic metres have been utilized for irrigation. India needs to plan these water resources to be utilized for agriculture. For this more multipurpose projects should be planned and completed. Ground water resource should be used for providing water power to tubewells. A lot has been done to manage our water resources, but due to technological and financial limitations, still much of water goes waste to oceans.

Question 5.
How the water can be conserved?
Answer:
Water is a vital resource for the development of economic activities. Water should be conserved in the following ways. Waters of ocean, river and lakes should not be polluted. It should he saved from urban waste and chemicals of industries. It should be recycled to use it again. Dams should be built across the rivers and lakes to store water in reservoirs.

Question 6.
Write a note on Deciduous forests.
Answer:
Deciduous forests shed their leaves in a specific season. In spring season, these leaves become green.’These are the most widespread forests in India. These are economically very important from the point of getting timber. These include Sal, Teak, Bamboo, Shisham and Khair trees.

Question 7.
What steps have been taken by Govt, of India for protection and conservation of wildlife? (P.S.E.B. 2020)
Answer:
Wildlife plays an important role in the human progress and civilisation. The primitive man had to depend on animals for food and other basic needs. Later on, man began to domesticate animals. Still hunting is carried on in many parts of the world. Many useful and valuable species are becoming extinct due to hunting or killing of animals. Man has upset the ecological balance by killing of birds and animals.

Many steps have been taken for the preservation of wildlife.

Parks and sanctuaries have been established in hilly areas and forests.
Hunting of some rare species of animals has been banned.
Public attention is focused on making efforts for the preservation of wildlife.
Wild animals like lion, tiger, deer, etc. are protected during closed season when they cannot be hunted.

III. Answer the following questions in about 125-130 words :

Question 1.
What are Natural Resources? Write down the types and importance of soils and natural vegetation.
Answer:
Natural Resources are free gifts provided by nature. These include land, water, soil, forests, wildlife, minerals, etc.
1. Soils: The main types of soils are :

Alluvial soils
Black soils
Red soils
Laterite soils
Forests and Mountain soils
Desert soils.

Importance: Soil is a valuable resource. It is required for cultivation of crops. Fertile soil is the basis of developed agriculture. It becomes more important for a country like India which is an agricultural country. Many types of soils are found in India and many types of crops are grown on it.

2. Vegetation: The following types of vegetation is found in India :

Evergreen forests
Deciduous forests
Desert forests
Mountain forests .
Delta forests.

Importance of Forests: Forests are a valuable resource like a river system, it is a multiple resource. Forests provide mankind with a number of products. Forests have greatly influenced human activities. Modem civilization depends more and more on forests.

Following are the direct and indirect advantages of forests :

Forests provide many things to meet our food requirements like wild fruits, nuts, berries, etc. Many tribes are dependent on gathering of these products in forests.
Forests are a source of timber for house-building, furniture-making, ship-building, etc.
Forests supply about 40% of fuel of the world. Wood has been the major source of fuel in house smelting industries and running locomotives.
Soft wood trees supply raw materials, wood pulp, paper, rayon industries.
Many products like rubber, pitch, gum, tanning materials, cork, camphor, fir, herbs, etc. are gathered from forests.
Forests provide plywood and fibre wood for packing purposes

Question 2.
How the water and wildlife can be conserved? Express your views.
Answer:
India is rich in fauna and flora. There is a great biological diversity in, India. There are about 90000 known species of animals. It has 2500 species of fish and 1200 species of birds. But many of these fauna have been destroyed by-man. Many rare species have become extinct in India. Our rich wildlife is rich heritage formed through centuries. It must be preserved. Many of the fauna are found only in India such as swamp deer, the one-horned rhinoceros, the bison, Kashmir stag, Nilgai, etc. These rare species are in danger of extinction.

The following measures have been taken for conserving and protecting wildlife as well as its bio diversity in the country. Wildlife is a gift of nature and a thing of beauty. Wildlife Act provides for the protection and conservation of these species.

For this purpose :

A network of 89 national parks, 490 sanctuaries and 13 biosphere reserves have been established.
Under Project Tiger 27 Tiger Projects in 14 states have been set up.
15 mangroves have already been identified for intensive conservation and management purpose.

Conservation and Management of Water Resources
1. Watershed Management. The management of the divide between two drainage basin called watershed is taken as a physiographic unit. The inter-basin management of water helps to divert water from surplus areas to scarcity areas. It also helps replenish ground water resources. It involves integrated development of two or diverse basins and saves on technical and financial resources.

2. Rainwater Harvesting. Rainwater is stored in roof top tanks, on ground Or underground tanks or check dams, percolation pits, etc. during rainy season and then it is used for irrigation, improving vegetation cover in dry season. While it increases productivity it also replenishes ground water resources.

IV. Map Skill

Question 1.
Show the following on the outline map of India :
1. Northern plains of India
2. Ganga and Brahmputra Rivers
3. Region of Alluvial soils
4. A state with black soil
5. An area of evergreen forests
6. A region with mountain and delta vegetation.
Answer:

V. Activity

Question 1.
Show eight types of soils on the map of India.
Answer:

PSEB 8th Class Social Science Guide Natural Resources Important Questions and Answers

Multiple Choice Questions :

Question 1.
Which one of the following is not a type of forest found in India?
(a) Evergreen forest
(b) Tidal forest
(c) Deciduous forest
(d) Desert forest.
Answer:
(b) Tidal forest.

Question 2.
Cutting down of trees is called :
(a) Afforestation
(b) Deforestation
(c) Slash and Burn
(d) Strip cropping
Answer:
(b) Deforestation.

Question 3.
Sunderbans is the habitat of :
(a) Tiger
(b) Lions
(c) Elephants
(d) Camels
Answer:
(a) Tiger.

Question 4.
Which is the oldest landmass of India?
(a) Northern Plain
(b) Peninsular Plateau
(c) Himalayas
(d) Aravallis.
Answer:
(b) Peninsular Plateau.

Question 5.
Natural vegetation and wildlife is found in :
(a) Biosphere
(b) Hydrosphere
(c) Atmosphere
(d) None of the above.
Answer:
(a) Biosphere.

Question 6.
Following picture shows a specific type of forests, names these forests.

(a) Evergreen forests
(b) Tidal forests
(c) Deciduous forests
(d) Deserts
Answer:
(a) Evergreen forests.

Question 7.
Study the following picture and give the answer what this picture is explained?

(a) Afforestation
(b) Deforestation
(c) Slash and Burn
(d) Strip Gopping
Answer:
(b) Deforestation.

Question 8.
Jhoolan Devi does the agricultural work with her family but her family is forced to migrate to other place to do agriculture due to reduction in soil fertility. What type of farming does this situation represent?
(a) Permanent agriculture
(b) Horticulture.
(c) Intensive agriculture
(d) Jhum cultivation.
Answer:
(d) Jhum cultivation.

Question 9.
How much part of total area of India is under forests? (P.S.E.B. 2020)
(a) 11.9%
(b) 52.2%
(c) 22.2%
(d) 32.2%.
Answer:
(c) 22.2%

Fill in the Blanks :

Question 1.
In India soils are of types.
Answer:
six

Question 2.
__________ is the upper most layer of the earth crust .
Answer:
soil

Question 3.
Land use depends on __________ factor.
Answer:
physical

Question 4.
Ice-sheets are found in __________
Answer:
greenland

Question 5.
About ________% of the total surface area of the earth is under water.
Answer:
71

True/False :

Question 1.
The original rock called Parent Rock.
Answer:
True

Question 2.
Pollution means contamination of natural resources.
Answer:
True

Question 3.
A dripping tap wastes 100 litres in a year.
Answer:
False

Question 4.
An average urban Indian uses about 35 litres of water everyday.
Answer:
False

Question 5.
Land suitable for agriculture is called Arabic land.
Answer:
True.

Very Short Answer Type Questions

Question 1.
Describe the distribution of Land and Water on earth.
Answer:
29%-Land and 71%-Water.

Question 2.
Why is there need for Afforestation in India?
Answer:
There should be at least 33% area under forests in India. But only 22.2% area is under forests in India. So there is need for growing trees on large scale.

Question 3.
What do you mean by culturable waste?
Answer:
Some land is culturable, but it is not cultivated due to some reasons. Such as scarcity of water, soil erosion, waterlogging, etc.

Question 4.
In which areas forest and mountain soils are found? State any two characteristics.
Answer:
These soils are found along forests and hill slopes.

Characteristics:

These have organic elements.
These lack in Potash, Phosphorus, Lime. Therefore, use of fertilizer is essential.

Question 5.
What are alluvial soils?
Answer:
Alluvial soils are formed by deposition of fine sediments. These sediments are brought by the river. Sea waves also deposit these along coasts. Alluvial soils are very fertile.

Question 6.
Why is black soil called cotton soils? Name one other name of it.
Answer:
Black soil is suitable for the cultivation of cotton. So it is called cotton soil. It is also called Regur soil.

Question 7.
Where are desert soils found in India?
Answer:
Desert soils are found in Rajasthan, Punjab, Haryana and in some parts of Gujarat.

Question 8.
Why is earth called a ‘watery planet’?
Answer:
Most of the earth (71%) is covered with water. So it is called watery planet due to excess of water.

Question 9.
In which form most of water is found on earth? How much per cent is it of total water?
Answer:
Most of water is found in the form of oceans, seas and salt lakes. It contains 97.20% of total water.

Question 10.
For which purpose, most of water is used and how much?
Answer:
93.37% of total water is used for agricultural purposes.

Question 11.
Where are Tanks found?
Answer:
Tanks are found in areas where there are no perennial rivers and canals. Ground water is very deep. In India most of tanks are found in southern India.

Question 12.
Write briefly about desert vegetation.
Answer:
Desert vegetation is found in arid areas. The vegetation is scanty. It includes Date palm, Cactus and Thorny bush. In India, this type of vegetation is found in Rajasthan, Gujarat and Haryana.

Question 13.
Name four trees of mountain vegetation.
Answer:

Fir
Deodar
Oak
Nuts.

Question 14.
What is terrace farming?
Answer:
Terrace farming. The growing of crops on level steps or terraces that have been constructed on hillsides.

Question 15.
What is a wildlife sanctuary?
Answer:
A wildlife sanctuary is dedicated to protect wildlife and conserve forests.

Question 16.
What are Protected forests?
Answer:
There are forests reserved for timber but grazing is allowed subject to minor restrictions. These are 29.2% of total forests.

Question 17.
What is contour ploughing?
Answer:
Contour Ploughing: Technique of ploughing parallel to the contours of a hill slope rather than up and down the slope, so as to reduce soil erosion.

Question 18.
What is strip cropping?
Answer:
Strip Cropping. Growing of different crops on parallel narrow strips of ground, usually following the contour patterns.

Question 19.
What is a shelterbelt?
Answer:
Shelter belt: In dry regions, rows of trees are planted to check the wind movement for protecting soil cover.

Short Answer Type Questions

Question 1.
Write a note on alluvial soils. Classify these into two groups.
Answer:
Alluvial soils. These cover 45% land of India :

Alluvial soil is deposited by rivers.
These soils are limited to river basins and plains.
These are very fertile soils.
These consist of fine-grained. clay and sand.
These soils are rich in potash, but poor in phosphorus.
These are usually deep soils.

Types:
(a) Khadar soils
(b) Bangar soils.

(a) Khadar soils are new alluvial soils while
(b) Bangar soils are old alluvial soils.

Question 2.
State the characteristics of Black soils. Describe its distribution in India.
Answer:
Black Soils. Black soils are mainly found over the Deccan Lava tract (Deccan trap) including Maharashtra, Madhya Pradesh, Gujarat and Andhra Pradesh. These soils are found in river valleys of Narmada, Tapti, Godavari and Krishna. These soils have

been formed due to weathering of lava rocks. These soils cover an area of about 5 lakh sq. km. These soils are rich in lime, iron, magnesia and alumina. But these lack in phosphorus, nitrogen and organic matter. These are also called ‘Regur Soils’. These soils are most suitable for cotton cultivation and are known as ‘Black Cotton Soils’. These soils are compared with Chernozem soils of Russia and Prairies soils of U.S.A. These soils can hold water. These soils are suitable for rice, wheat, jawar, sugarcane, tobacco and oilseeds.

Question 3.
Write a note on desert soils.
Answer:
Desert Soils. These soils cover 2 lakh sq. km. area in dry areas of Rajasthan, Gujarat, Punjab, Haryana. These coarse soils are suitable for the cultivation of jawar, bajra, cotton, oats, maize, pulses etc. Methods of irrigation are used. These are sandy soils and are infertile. These do not hold water. So these are used for dry crops. In India 4.3% area is covered by desert soils.

Question 4.
State the characteristics and distribution of Red Soils in India.
Answer:
Red Soils: These soils are found in Chotta Nagpur plateau, Telangana, Nilgiris, Tamil Nadu, Karnataka, Andhra Pradesh and areas on periphery of Deccan Plateau. These soils have been formed due to decomposition of underlying igneous rocks under heavy rainfall. These soils have different shades of red and yellow. The red colour of these soils is due to oxidation and diffusion of iron in hard crystalline rocks. These are used for the cultivation of millets, pulses, linseed, tobacco, etc. These soils cover the largest area (10.6%) in Peninsular India, particularly S.E. part of the Peninsula. These soils are poor in lime, nitrogen and humus. Fertilizers are added to make these fertile.

Question 5.
What are the characteristics of laterite soils? Describe its distribution in India.
Answer:

The laterite soils are of brick colour.
These are shallow, acidic and less fertile.
These are less fertile due to leaching of soil.
These are poor in nitrogen, potash but very rich in iron.
These are found in Tamil Nadu, Western Ghats, Rajmahal hills, Vindhyas, Satpuras and Malwa plateau. These soils cover 7.5% area of the country
Some areas of Maharashtra, Andhra Pradesh, Orissa, Karnataka, Jharkhand also have laterite soils.
These are suitable for cultivation of Rubber, Tea, Coffee and Coconut.

Question 6.
What do you mean by wildlife? Describe in brief the wildlife of India.
Answer:
Like diverse flora, our fauna is found to be equally rich and varied. There are about 80,000 known species. The country in its fresh and marine waters has as many as 2500 species of fish. Likewise there are about 1200 species of birds. In addition there are amphibians, reptiles, mammals and small insects and worms. Migratory birds also come to India during winter

Mammals: Among the mammals, the elephant is the stately animal. It is a typical animal of hot wet equatorial forests. It is found in the jungles of Assam, Kerala and Karnataka. In these areas, it rains heavily and the forests are very dense. On the other hand camels and wild asses are found in hot deserts. Camels are found in Thar desert.

Question 7.
Why is the Land considered an important resource?
Answer:
Land is considered as an important resource because:

It is used for different purposes like agriculture, forests, pastures.
Human beings make their houses and live on it and also it provides most of the products they need; like food, wood etc.

Question 8.
Name the five factors controlling soil formation.
Answer:
The five factors controlling soil formation are:

Nature of the parent rock
Topography
Climate
Time
Organism in it.

Question 9.
Write any two reasons for land degradation today.
Answer:
There are many factors which lead to the degradation of land. Both nature and human factors can lead to degradation of land.

Growing population and their ever growing demand is the main reason of land degradation today.
Deforestation is the another main reason of land degradation.

Question 10.
Why is land considered an important resource?
Answer:
Land is considered as an important resource because :

It is used for different purposes such as agriculture, forest, mining, pastures, etc.
Human beings make their houses and five on it and also it provides most of products they need like food, wood, etc.
Human beings set up their industries, build roads and run other commercial activities.

Question 11.
What factors control the utilization of land?
Answer:
The physical and human factors control the utilization of land. These include :

relief of features,
climatic conditions,
soils,
density of population,
technical level of the people,
land tenure,
duration of the occupation of the area etc.

The interplay of physical and human factors has developed many types of land uses.

Question 12.
What is terrace farming?
Answer:
Terrace farming: The growing of crops on level steps or terraces that have been constructed on hillsides.

Question 13.
What is a wildlife sanctuary?
Answer:
A wildlife sanctuary is dedicated to protect wildlife and conserve forests.

Question 14.
What are the effects of deforestation?
Answer:
The effects of deforestation are as under :

It affects the ecosystem.
It increases soil erosion.
It affects underground flow of water.
Disappearance of wildlife as well as variety of plants.
Leads to serious deterioration of genetic reserves.

Question 15.
What are Protected forests?
Answer:
These are also forests reserved for timber but grazing is allowed subject to minor restrictions. These are 29.2% of total forests.

Question 16.
What is contour ploughing?
Answer:
Contour ploughing: Technique of ploughing parallel to the contours of a hill slope rather than up and down the slope, so as to reduce soil erosion.

Question 17.
What is strip cropping?
Answer:
Strip Cropping. Growing of different crops on parallel narrow strips of ground, usually following the contour patterns.

Question 18.
For what purposes land is used? What is land use pattern?
Answer:
Land is used for different purposes.

They are :

Cultivation of crops agriculture.
Grazing of animals.
Building houses and roads.
Mining.
Industries.

These uses of land is commonly termed as land use pattern.

Question 19.
What is a shelterbelt?
Answer:
Shelterbelt: In dry regions, rows of trees are planted to check the wind movement for protecting soil cover.

Question 20.
Write the importance of forests.
Answer:
Importance of forests. Forests play an important role in human life. They provide food, wood and timber to us. Many medicinal plants are found in the forests. They also help in maintaining ecological balance and checking soil erosion. They play an important role in the economy of our country.

Question 21.
What is the role of insects in soil formation?
Answer:
Insects play a very important role in soil formation. Without worms and insects, the work of soil formation will be incomplete. They do it through both physical or mechanical means and speeding up chemical reactions.

Question 22.
Why does soil lose fertility?.
Answer:
The soil loses its fertility when continuously used. When crops are grown every year it loses its nutrients which are necessary for good soil.

Question 23.
What are the factors that control soil formation?
Answer:
Soil formation is controlled by five factors. These are :

Nature of parent rock
The topography
The climate
The organism in the soil
Time.

Question 24.
What is the importance of landforms?
Answer:
Man’s economic activities differ with different landforms.

Mountainous regions are not much suitable for human settlements.
Dense population is found in plains.

Question 25.
‘Land plays a fundamental role.’ Discuss.
Answer:
Plains are known for agriculture and dense population. Plains, 43% area of India, fulfill man’s many needs. The agriculture depends upon plain.

Question 26.
What is fallow land?
Answer:
The land which is not used for agriculture for 1 to 5 years is left vacant. It restores the fertility of the soil. It is called fallow land.

Question 27.
Examine the importance of water.
Answer:
Water is a valuable and important resource. It is the basis of life on earth. Water fulfils many human requirements. It is used for drinking, bathing, washing and agriculture.

Question 28.
Name the major threats to be environment.
Answer:
Land degradation, landslides, soil erosion and desertification are the major threats to the environment. This is because of expansion of agriculture and construction activities.

Question 29.
Write the steps that can help in conserving degraded land.
Answer:
The following steps may help in conservation and reclamation of degraded land:

Afforestation and control on overgrazing.
Plantation of land reclamation of plants.
Regulated use of chemical pesticides and fertilisers.
Proper discharge of sewage industrial effluents.
Maintain proper mining processes and technique.

Fill in the blanks :

Question 1.
Nearly 97% of the earth’s total water is in the form of __________ and __________
Answer:
Sea, oceans

Question 2.
Tiger park at Dudhwa is situated in the state __________
Answer:
Uttar Pradesh

Question 3.
__________ is produced with the help of running and falling water.
Answer:
Hydro-electricity

Question 4.
Polar areas are populated areas.
Answer:
sparsely

Question 5.
We can __________ the supply of drinking water by installing desalination plants.
Answer:
increase

Question 6.
In __________ areas landslides have been a major and widely spread natural disaster.
Answer:
mountains.

Long Answer Type Questions

Question 1.
What are the sources of fresh water in India? Describe each.
Answer:
Two types of water is found on earth-saline and fresh. Man uses freshwater for different purposes. Its sources are :
1. Rainfall. Rainfall is the major source of water on the earth. Some water is evaporated, some water flows down to the oceans and some water goes underground through percolation. India has average annual rainfall of 118 cm.
Rain water or running water flowing on the surface of land is called surface water. It includes water in oceans, seas, lakes, rivers, etc. India’s total surface water resources are 1869 billion cubic metres.

2. Ground Water. Rain water that goes beneath the surface of the earth by percolation is called ground water. India has a total ground water resources of 40 million hectare metres. This water can be obtained by digging wells. Sometimes it comes out through springs also.

3. Rivers and Canals. From early periods, rivers and canals have been very important. Many civilisations developed along river banks. Man built dams on rivers to use water for irrigation through canals.

4. Tanks. Tanks are found in areas deficit in rainfall. The water level is very deep so it is difficult to use it. Rain water is collected in depressions called tanks. Tanks are mostly found in southern India.

Question 2.
What do you mean by Natural Vegetation? On what factors does it depend? Describe the different types of forests found in India.
Answer:
Natural vegetation includes plants and trees which grow automatically according to climate. It depends upon climate, soil, drainage, temperature, rainfall and altitude.

We can divide India into the following vegetation belts :

The Tropical Rain Forests.
The Tropical deciduous or the Monsoon forests.
The Thorn Forests.
The Tidal Forests.
Mountain Forests.

1. The Tropical Rain Forests are of two varieties: evergreen and semi-evergreen. Regions having more than 300 centimetres of rainfall have evergreen forests. The hills of Assam and the rainy slopes of the Western Ghats are such areas. The region where the rainfall is between 200 and 300 centimetres have semi-evergreen forests. Such areas are there in Assam, West Bengal, Orissa and in Western Ghats.

2. The Tropical Deciduous or Monsoon Forests are found in the regions where rainfall is between 100 and 200 centimetres. Teak and sal are the most important trees of monsoon forests besides sheesham, mahua, bamboo, etc. The belt of monsoon forests extends from the Western Ghats in the south to the Shiwalik hills in the north.

3. The Thorn Forests are found in Rajasthan, Haryana, Punjab, Gujarat, dry parts of Madhya Pradesh and the Deccan, where the rainfall is less than 80 centimetres. Kikar, Babool and Wild Palm are the common trees of this type of forests.

4. The Tidal Forests are mainly found along the river deltas. Mangrove and Sundri trees are the common trees found in the Ganga delta in Bengal which is also “called the Sundarban.

5. The Mountainous Forests. The foothills of the Himalayas are covered with tropical deciduous forests. At high slopes, oak, chestnuts, chir, pine trees of sub-tropical type are formed. At a height of 3300 metres, coniferous forests like blue pines, cedars silver firs, deodars are found. Alpine pastures are found at high altitudes.

Question 3.
Write a short note on conservation of soils.
Answer:
Soil Conservation. Soil is a fundamental natural resource. Soil formation is a slow process, but it is easily lost by soil erosion. In fact, more soil is being lost each year than nature makes. Soil erosion must be checked. Sound farming practices and measures be adopted to conserve, protect, renew and maintain soil fertility.

These methods constitute soil conservation.
1. Afforestation: In some areas, the original vegetation cover has been removed such as in Shiwalik hills. In such areas afforestation and reforestation is needed to hold the soil. Advance of deserts can be checked by planting trees along the margins of deserts.

2. Controlled grazing: The number of cattle to be grazed on slopes should be according to the carrying capacity of the pastures.

3. Terraced agriculture: Slopes must be cut into a series of terraces (fields) for the cultivation so as to slow down the flow of rain water.

4. Contour Ploughing: It is done to check soil wash on slopes. Ploughing is done at right angles to the hill slopes.

5. Crop rotation: Crop rotation system be applied and the land should be allowed fallow for some time. Soil fertility can be maintained in this way.

Question 4.
Distinguish between Evergreen Forests and Deciduous Forests.
Answer:

Evergreen Forests	Deciduous Forests
1. Evergreen forests are found in regions that experience tropical climate throughout the year.	1. Deciduous forests are found in regions that experience rainy and dry season.
2. They do not shed their leaves in any season of the year.	2. They shed their leaves once a year.
3. Their height exceeds 60 metres.	3. They are less than 50 metres in height.
4. They have less economic importance as the wood from them is very hard and is of not much use.	4. They have more economic value, as their wood is soft and durable.
5. Some trees are ; Rosewood, Mahogany etc.	5. Some trees are ; Teak, Sal, etc.

Question 5.

What is the most important feature of the Landuse pattern in India?
Answer:

India has total geographical area of 828 million sq. km. (3280 lakh hectares). The land use data is available for about 93% of the total area. It shows that 151 million hectares (47%) is net sown area. Thus India has a very high percentage (47%) of total area under cultivation. No other big country has such a large area under cultivation.
Another satisfying feature is that only 8% of land is fallow which is not cultivated so as to restore the fertility of the land. It is notable that fallow land has risen to 8% from earlier figure of 5%. It reflects that care for land resources has become essential.
The area under pastures is also small (4%).
The area under cultivable waste is 5%. This wasteland can be brought under cultivation to increase productivity.
The forest cover is low, only 22%. It is desirable to have about one third of the total land area under forests to maintain a healthy environment.

Question 6.
Explain the factors controlling soil formation.
Answer:
Soil formation is controlled by five factors :

nature of parent rock,
the topography,
the climate,
the organism in the soil and
time.

1. Parent Rock: The original rock called parent rock, from which the soil is formed, determines its basic characteristics. For example, shales contribute clays, while sandstones contribute sand grains.

2. Climate: Temperature and precipitation are the main climatic factors affecting soil formation. Frequent temperature changes and presence of water quicken soil formation through increased weathering.

3. Topography: Topography affects the drainage of an area. On a steep slope, there is hardly any chance of accumulation of weathered rocks. They are moved down the slope by water and under force of gravity. In plains and areas with gentle slope, soils are accumulated without any hindrance.

4. Organisms: Dead plants and animals provide humus to soil. Organisms like earthworms and ants through their movements create space for air and water in the soil.

5. Time: Time factor is also important because longer the time for soil formation, more deeper is the soil layer. Besides weathering of rocks, soil is also formed by deposition of materials by moving waters (rivers) and winds in low-lying areas. Alluvial soils of river valleys are very fertile and deep.

Question 7.
What are water resources? What are their uses?
Answer:
Water Resources. Water is a unique liquid because there is no alternative for it. It is essential for all forms of life. Compared to most other liquids, water has a high capacity to absorb or store heat.

Water is a major body constituent of several plant and animal species. Seventy percent of the human body consists of water. Humans use water for several purposes—domestic (drinking, cooking, washing, etc.), agricultural (irrigation), industrial and generation of electricity.

Question 8.
How are vegetation and wildlife useful for us?
Answer:
Vegetation and wildlife are valuable resources
1. Plants provide us

Timber, fruits, nuts, latex, oil, gum, medicinal herbs, etc.
Shelter for animals and birds.
Protect soil and storage and water.
Oxygen to breathe.

2. Wildlife provides us

with milk, meat, hides, wool, honey.
helps as decomposers, act as scavengers.
maintain the ecological balance.
The birds feed on insects and act as decomposers as well.
Vulture each dead livestock and act as scavengers. They are considered as a vital cleaner of environment.

PSEB 8th Class Science Solutions Chapter 6 Combustion and Flame

September 26, 2024September 25, 2024 by Prasanna

Punjab State Board PSEB 8th Class Science Book Solutions Chapter 6 Combustion and Flame Textbook Exercise Questions and Answers.

PSEB Solutions for Class 8 Science Chapter 6 Combustion and Flame

PSEB 8th Class Science Guide Combustion and Flame Textbook Questions and Answers

Exercises

Question 1.
List conditions under which combustion can take place.
Answer:
Conditions necessary for combustion:

Presence of a combustible substance.
Presence of a supporter of combustion.
Attainment of ignition temperature.

Question 2.
Fill in the blanks.
(a) Burning of wood and coal causes ……………… of air.
(b) A liquid fuel, used in homes is ………………
(c) Fuel must be heated to its …………………………………… before it starts burning.
(d) Fire produced by oil cannot be controlled by …………………..
Answer:
(a) Pollution.
(b) Kerosene.
(c) Ignition temperature.
(d) Water.

Question 3.
Explain how the use of CNG in automobiles has reduced pollution in our cities.
Answer:
CNG is a clean gaseous fuel. It burns completely in air and does not produce any harmful gases. So, the use of CNG in automobiles has reduced pollution in our cities.

Question 4.
Compare LPG and wood as fuels.
Answer:
LPG is a clean fuel. It is liquefied petroleum gas and is filled in cylinders. It burns with a blue flame and leaves no residue. Its calorific value is high. Wood is not a clean fuel. It burns and release lots of smoke and ashes are left behind. It give very low amount of heat.

Question 5.
Give reasons:
(a) Water is not used to control fires involving electrical equipment.
(b) LPG is a better domestic fuel than wood.
(c) Paper by itself catches fire easily whereas a piece of paper wrapped around an aluminium pipe does not.
Answer:
(a) The substance used for extinguishing fires on electrical appliances or circuit should not be good conductor of electricity as there are chances of electrocution. So, water being a good conductor of electricity, is not used for extinguishing fires on electrical appliances or circuit. Carbon-tetrachloride (non-electrolyte) is used for this purpose.

(b) LPG is liquefied petroleum gas. It has high calorific value of 50 kJ/g. It is neat and clean fuel. It burns with a smokeless flame and does not produce poisonous gases. While wood has less calorific value of 17 kJ/g. It gives out smoke and poisonous gases on burning. So, LPG is better fuel than wood.

(c) When paper wrapped around an aluminium pipe is brought near a flame, it does not burn because the heat gets transferred to aluminium pipe and the ignition temperature of paper is not achieved.

Question 6.
Make a labelled diagram of a candle flame.
Answer:
PSEB 8th Class Science Solutions Chapter 6 Combustion and Flame 1

Question 7.
Name the unit in which the calorific value of a fuel is expressed.
Answer:
Kilojoules per kilogram (kJ/kg).

Question 8.
Explain how CO₂ is able to control fires.
Answer:
CO₂ gas is heavier than air. So, it forms an envelope around the burning fire. This, cuts off the supply of oxygen gas and fire stops burning and gets under control.

Question 9.
It is difficult to burn a heap of green leaves but dry leaves catch fire easily. Explain.
Answer:
Green leaves have a high moisture content in them and in the heap of green leaves, oxygen present is very less. Whereas dry leaves have no moisture content and there is lot of oxygen available in this heap. So, it is difficult to burn a heap of green leaves than a heap of dry leaves.

Question 10.
Which zone of flame does a goldsmith use for melting gold and silver and why ?
Answer:
Goldsmith usually uses the upper most, non-luminous, blue flame for melting gold and silver because it is the hottest part of the flame.

Question 11.
In an experiment 4.5 kg of a fuel was completely burnt. The heat produced was measured to be 180,000 kJ. Calculate the calorific value of the fuel.
Solution:
Mass of fuel = 4.5 kg
Heat produced = 180,000 kg
Now, Calorific value of a substance = \(=\frac{\text { Heat produced }}{\text { Mass }}\)
= \(\frac{180,000}{4 \cdot 5}\) kj/kg
= \(\frac{40,000}{1}\)
= 4 × 10⁴ kj/kg

Question 12.
Can the process of rusting be called combustion ? Discuss.
Answer:
Rusting.
When iron is exposed to moist air, it gets coated with hydrated iron oxide. This process is called rusting and the coating formed is called rust. Chemically rust is hydrated form of ferric oxide, Fe₂O₃. xH₂O. It is reddish brown in colour.
The overall reaction for rusting is:
PSEB 8th Class Science Solutions Chapter 6 Combustion and Flame 2
Combustion is an oxidation reaction and rusting is also an oxidation reaction but very slow. So, rusting can be termed as slow combustion reaction.

Question 13.
Abida and Ramesh were doing an experiment in which water was to be heated in a beaker. Abida kept the beaker near the wick in the yellow part of the candle flame. Ramesh kept the beaker in the outermost part of the flame. Whose water will get heated in a shorter time.
Answer:
Ramesh’s beaker will get heated in a shorter time because the outermost part of flame is the hottest part.

PSEB Solutions for Class 8 Science Combustion and Flame Important Questions and Answers

Multiple Choice Questions

Question 1.
With the help of the following diagram tell the colour of its flame?
PSEB 8th Class Science Solutions Chapter 6 Combustion and Flame 3
Answer:
The colour of the flame of lamp: yellow
The colour of the flame of candle : yellow
The colour of the flame of bunsen burner : blue.

Question 2.
In the figure below various parts of candle flame are given. Tell which one of them is less hot ?
PSEB 8th Class Science Solutions Chapter 6 Combustion and Flame 4
(а) Outer Zone
(б) Inner Zone
(c) Middle Zone
(d) None of these.
Answer:
(c) Middle Zone.

Question 3.
Fuel is:
(a) Solid
(b) Liquid
(e) Gas
(d) Solid, liquid and gas
Answer:
(d) Solid, liquid and gas

Question 4.
Which of the following gas is supporter in combustion?
(a) Oxygen gas
(b) L.P.G.
(e) Nitrogen gas
(d) Carbondioxide gas
Answer:
(a) Oxygen gas.

Question 5.
Which of the following is combustible substance ?
(a) Iron nail
(b) Glass
(c) Paper
(d) A piece of stone
Answer:
(c) Paper

Question 6.
The conditions for combustion are:
(a) Fuel and air
(b) Fuel, air and ignition temperature
(c) Fuel and ignition temperature
(d) Air and ignition temperature.
Answer:
(b) Fuel, air and ignition temperature.

Question 7.
Which out of the following has minimum ignition temperature ?
(a) Petrol
(b) Kerosene
(c) Coal
(d) L.P.G.
Answer:
(d) L.P.G.

Question 8.
Which of the following gas causes acid rain ?
(a) H₂
(b) N₂
(c) Carbon-monoxide
(d) Oxides of sulphur and nitrogen
Answer:
(d) Oxides of sulphur and nitrogen.

Question 9.
While extinguishing fire of electric wires and electric instruments, which of the following item is not used ?
(a) Sand
(b) Water
(c) Foam
(d) Carbondioxide
Answer:
(b) Water.

Question 10.
The unit of Calorific value of a fuel is:
(a) Joule
(b) Kilo joule/kg
(c) Kilo joule
(d) None of the above.
Answer:
(b) Kilo joule/kg.

Very Short Answer Type Questions

Question 1.
List the fuels used in rural areas in our country.
Answer:
Wood, agricultural wastes and cow-dung cakes.

Question 2.
Which of the following solid fuels has the highest heat value: Cow-dung cakes, coal, wood?
Answer:
Coal.

Question 3.
Name the most commonly used liquid fuel in Indian homes.
Answer:
Kerosene.

Question 4.
Name three liquid fuels.
Answer:
Kerosene oil, Petrol, Diesel.

Question 5.
When fuels burn, what do they produce?
Answer:
Heat and light.

Question 6.
What is ignition temperature?
Answer:
Ignition temperature. The lowest temperature at which a substance catches fire in the presence of oxygen, is called its ignition temperature.

Question 7.
Name two liquids which have low ignition temperatures.
Answer:

Alcohol and
ether.

Question 8.
What type of fire èxtinguisher is used to extinguish fire caused by
electricity?
Answer:
Carbon tetrachioride (CCl₄) fire extinguisher.

Question 9.
What is combustion ?
Answer:
Combustion.
It is the process of heating of a substance in the presence of oxygen with the evolution of heat and light.
It is an oxidation reaction in which substance (fuel) burns in the presence of oxygen so as to liberate heat and light.

Question 10.
Define heat value of a fuel.
Answer:
Heat value of fuel. The amount of heat liberated when 1 kg of substance is burned, is called heat value of that fuel.

Question 11.
Name the type of fire extinguisher used for extinguishing oil fires.
Answer:
Foam type fire extinguisher.

Question 12.
Why charcoal is considered better fuel than wood ?
Answer:
It is because calorific value of charcoal is higher than that of wood.

Question 13.
Name the zones of a candle flame.
Answer:

Cold innermost zone,
middle zone,
outermost non-luminous zone.

Question 14.
Name two substances which may be effective in fire fighting.
Answer:
Water and Foam.

Question 15.
Name three combustible substances.
Answer:
Paper, wood and cooking gas are three combustible substances.

Short Answer Type Questions

Question 1.
What are fuels ? In which different states fuels are found?
Answer:
Fuels. The materials which are burnt to produce heat and light, are called
fuels.
Fuels are found in three states:

Solid (wood, coal, charcoal etc.)
Liquid (petrol, kerosene, diesel)
Gases (natural gas, coal gas, bio-gas etc).
Fuels are found in Maharashtra and Gujarat states.

Question 2.
How will you prove that air is required for combustion?
Answer:
A burning coal or wood piece stops burning after some time, if it is covered with a glass vessel. This is because the supply of air is cut off, which stops combustion. If air is blown on this burning piece, it again starts burning with a blaze. It is therefore, concluded that air (supporter of combustion) is required for burning of a substance.

Question 3.
How can accidental fires be extinguished?
Answer:
Accidental fires can be extinguished by controlling any one of the three conditions responsible for producing fire:

by cutting supply of air (oxygen) so that the combustible substance does not come in contact with the supporter of combustion.
by cooling the burning substance or by lowering its ignition temperature.
by removing nearby combustible substances so that fire does not spread.

Question 4.
Why do Goldsmiths use a blow-pipe?
Answer:
Goldsmiths use a blow-pipe to intensify a kerosene lamp flame for moulding pieces of gold or silver into desired shapes. The air blown through the pipe aids combustion of unburnt particles of fuel, thereby making the flame hotter.

Question 5.
Why do combustible substances not catch fire on their own ?
Answer:
Combustible substances cannot catch fire on their own as their ignition temperature is higher than normal temperature. When the temperature is lowered than ignition temperature, they catch fire.

Question 6.
Explain Ignition temperature, combustible substance, supporter of combustion in reference to conditions of combustion.
Answer:
Ignition temperature is the minimum temperature at which fuel catches fire. Each substance has definite ignition temperature below which it will not catch fire.

Combustible substance is that which readily catches fire. Paper, LPG, cloth etc. are combustible substances.

Supporter of combustion is that substance which helps in burning the combustible substance. Combustible substances like petrol, LPG will not burn till supporter of combustion like oxygen is supplied in ample amount.

Question 7.
Given the reaction:
C + O₂ → CO₂ + 385 kJ
Calculate the calorific value of carbon (atomic weight of C = 12, O = 16).
Solution:
According to equation, 1 mole of carbon or 12 g of carbon on burning produce 385 kJ of heat.
Thus
12 g of carbon produce heat = 385 kJ
1 g of carbon produces heat = \(\frac{385}{12}\)
∴ Calorific value of carbon = 32.1 kJ/g

Question 8.
Why is a match stick lighted on rubbing it on the rough surface provided on the side of the match box ?
Answer:
This is due to the fact that when we rub the match stick on the rough surface of the match box, the work done during rubbing produces heat due to friction. This heat raises the temperature of the chemical present on the match stick head to its ignition temperature. Therefore, the chemical substance catches fire and the match stick starts burning.

Question 9.
Why is coke considered a better fuel than coal ? Give four reasons.
Answer:
Coke is considered a better fuel than coal because of the following reasons:

Coke has higher calorific value than coal.
Ignition temperature of coke is less than that of coal.
Coke produces less smoke than coal.
Coal on burning produces some pollutants like CO₂, CO and small quantities of SO₂ whereas coke does not
produce these pollutants.

Question 10.
What do you mean by fire fighting ?
Answer:
Fire Fighting.
By fire fighting we mean to put out the fire. A fire may be due to an accident, short circuiting or human negligence. The combustion of a substance requires combustible substances, oxygen (or air) and heat. Therefore, to put out fire the air or oxygen supply should be cut off.

Question 11.
What should you do to put out the fire ?
Answer:
A fire may be due to an accident, short circuiting or human negligence. The combustion of a substance requires combustible substance, oxygen and heat. Therefore, to put out fire the air supply should be cut off. The fire can be put out by using carbon dioxide, water, sand etc.

Question 12.
Why should water not be used to extinguish fire due to :
(i) Kerosene or Petrol
(ii) Short circuiting ?
Answer:
(i) This is because kerosene and petrol being lighter than water, float on it and may further spread fire.

(ii) This is because water conducts electricity and it can cause a fatal shock to the person who is putting out the fire.

Question 13.
Why do we wrap a blanket around a person who has caught in lire ?
Answer:
When a person is caught in fire is wrapped with blanket does not get proper supply of oxygen which is necessary for combustion to take place.

Question 14.
Why are we advised not to sleep in a room with a burning coal ingithi in it ?
Answer:
In a closed room there is limited supply of oxygen and due to incomplete combustion of coal, carbon monooxide gas is produced. This gas is poisonous and may prove fatal. So we are advised not to sleep in a closed room with burning coal ingithi in it.

Question 15.
Explain Global warming.
Answer:
Global Warming. Combustion of most fuels releases carbondioxide in the air resulting in the increase of temperature of the atmosphere which is believed to be the cause of Global warming. Global warming results in melting of polar glaciers causing floods in the low lying coastal areas.

Question 16.
What is acid rain ?
Answer:
Acid Rain.
Burning of coal and diesel releases sulphur dioxide gas which is very pungent and suffocating. Moreover, petrol engines give off oxides of nitrogen. These oxides of sulphur and nitrogen dissolve in water of rain to form acids. Such rain is called Acid rain.

Question 17.
Why does the flame shown in the picture extinguishes when a glass jar is put on the burning candle ?
PSEB 8th Class Science Solutions Chapter 6 Combustion and Flame 5
Answer:
We know that oxygen is necessary for burning but when we put a glass jar on the burning candle, the amount of oxygen becomes less. The flame of candle extinguishes because of shortage of oxygen.

Long Answer Type Questions

Question 1.
Discuss the various combustion zones of a candle flame with the help of a diagram.
or
Explain the zones of candle with the help of a diagram.
Answer:
PSEB 8th Class Science Solutions Chapter 6 Combustion and Flame 6
A candle flame has three distinct zones.
1. Dark inner Zone
2. Luminous Zone
3. Non-luminous Zone.

1. Dark inner zone.
The innermost zone is dafk and is the coldest part of the flame. It consists largely of the hot vapours of wax (the combustible material). Introduce one end of a glass tube in the zone, you will see white vapours coming out from the other end of the tube. On being lighted with a matchstick, these emerging vapours burn with a flame.

2. Luminous Zone.
The middle zone is a bright luminous zone. In this zone the fuel partially burns forming carbon particles. It is the glow of these particles that makes this zone luminous. The carbon particles leave the flame as smoke and soot.

3. Non-luminous Zone.
It is the outer zone which is faintly bluish in colour. In this zone oxygen from the air mixes with the fuel bringing about complete combustion. This zone is the outermost non-luminous zone. It has the highest temperature of around 1800°C.

Question 2.
Describe
(i) Rapid combustion
(ii) Spontaneous combustion
(iii) Slow combustion
(iv) Explosion.
Answer:
(i) Rapid Combustion.
The oxidation reaction in which heat and light is produced in a short time is called rapid combustion. For example, when a burning splinter is brought near the gas burner, the gas tap of which is opened, the gas immediately starts burning with the production of heat and light. Similarly, a candle starts burning when a burning splinter is brought close to its wick.

(ii) Spontaneous Combustion.
Combustion which takes place without the application of any external heat is known as spontaneous combustion.
White phosphorus is the best example of a substance burning with spontaneous combustion.

(iii) Slow Combustion.
It is a slow oxidation process in which no light is produced. In such a reaction the heat liberated is at such a low rate that we cannot feel it.
Rusting of iron and the process of respiration are examples of slow combustion.

(iv) Explosion.
Such a process of combustion, where a large number of gases with the evolution of the tremendous amount of heat and light are evolved is called an explosion. During the Diwali festival, we observe that certain crackers explode only when pressure is applied. In this process, the oxidation of the chemicals in the cracker takes place at a very high speed. Large amounts of gases are liberated with the evolution of a tremendous amount of heat and light.
Gunshot, when fired, is called an explosion.

PSEB 8th Class Science Solutions Chapter 2 Microorganisms: Friend and Foe

September 26, 2024September 25, 2024 by Prasanna

Punjab State Board PSEB 8th Class Science Book Solutions Chapter 2 Microorganisms: Friend and Foe Textbook Exercise Questions and Answers.

PSEB Solutions for Class 8 Science Chapter 2 Microorganisms: Friend and Foe

PSEB 8th Class Science Guide Microorganisms: Friend and Foe Textbook Questions and Answers

Exercises

Question 1.
Fill in the blanks:
(а) Micro-organisms can be seen with the help of a ……………. .
Answer:
microscope

(b) Blue green algae fix ……………….. directly from air to enhance fertility of soil.
Answer:
nitrogen

(d) Cholera is caused by ……………. .
Answer:
bacteria

Question 2.
Tick the correct answer:
(a) Yeast is used in the production of:
(i) sugar
(ii) alcohol
(iii) hydrochloric acid
(iv) oxygen.
Answer:
(ii) alcohol

(b) The following is an antibiotic :
(i) Sodium bicarbonate
(ii) Streptomycin
(iii) Alcohol
(iv) Yeast.
Answer:
(ii) streptomycin.

(c) Carrier of malaria-causing protozoan is:
(i) female anopheles mosquito
(ii) cockroach
(iii) housefly
(iv) butterfly.
Answer:
(i) female anopheles mosquito.

(d) The most common carrier of communicable diseases is :
(i) ant
(ii) housefly
(iii) dragonfly
(iv) spider.
Answer:
(ii) housefly.

(e) The bread of idli dough rises because of:
(i) heat
(ii) grinding
(iii) growth of yeast cells
(iv) kneading.
Answer:
(iii) growth of yeast cell.

(f) The process of conversion of sugar into alcohol is called:
(i) nitrogen fixation
(ii) moulding
(iii) fermentation
(iv) infection.
Answer:
(iii) fermentation.

Question 3.
Match the organisms in Column ‘A’ with their action in Column ‘B’

Column A	Column B
(i) Bacteria	(a) Fixing nitrogen
(ii) Rhizobium	(b) Setting of curd
(iii) Lactobacillus	(c) Baking of bread
(iv) Yeast	(d) Causing malaria
(v) A protozoan	(e) Causing cholera
(vi) A virus	(f) Causing AIDS
	(g) Producing antibodies

Answer:

Column A	Column B
(i) Bacteria	(а) Causing cholera
(ii) Rhizobium	(b) Fixing nitrogen
(iii) Lactobacillus	(c) Setting of curd
(iv) Yeast	(d) Baking of bread
(v) A protozoan	(e) Causing malaria
(vi) A virus	(f) Causing AIDS

Question 4.
Can micro-organisms be seen with the naked eye ? If not, how can they be seen ?
Answer:
No, micro-organisms cannot be seen with naked eye because they are too small. So, we can only see them under microscope.

Question 5.
What are the major groups of micro-organisms ?
Answer:
The various groups of micro-organisms are:

Bacteria
fungi
protozoa
algae
virus.

Question 6.
Name the micro-organisms which can fix atmospheric nitrogen in the soil.
Answer:

Rhizobium bacteria
Blue green algae.

Question 7.
Write 10 lines on the usefulness of microorganisms in our lives.
Answer:
Micro-organisms are bacteria, fungi, algae and protozoans. The beneficial aspects of Micro-organisms are as given ahead:
Beneficial aspects of Bacteria:

Formation of milk products like curd and cheese.
Tenderization of meat by breaking down tough muscle fibre.
Formation of vinegar and wines.
Decomposition of organic matter.
Tanning of leather.
Conversion of atmospheric nitrogen to usable nitrogenous compounds.

Beneficial aspects of Fungi:

Production of bakery products like bread and cakes.
Other products like idli, dosa, processed cheese, etc.
Beverages like wines, beers, etc.
Mushrooms are edible fungi.
Medicines such as penicillin are made from fungi.

Beneficial aspects of Algae:
They help in the production of organic matter through photosynthesis which provides food to aquatic animals.

Algae cell extracts like agar and alginic acid are used for preparing medicines, food and cosmetics, etc. Kelp that is a brown algae is a rich source of iodine and potassium.
The cell walls of diatom (an alga) are a natural source of fine silica.
Many sea weeds are used as food in China and Japan.

Beneficial aspects of Protozoans:

They form an important link in the food chain.
They feed on fungi and bacteria. Mix it with potato glucose solution prepared earlier. Store the mixture so obtained in the suitable container. The PDA medium is ready and can now be used to culture microorganisms in petri dishes or test tubes.

Question 8.
Write a short paragraph on the harms caused by microorganisms.
Answer:
Harmful effects of Microorganisms:
1. These microorganisms cause a large variety of diseases in plants, animals and human beings.
2. They spoil food items as well as other articles like clothes, leather etc.
3. Micro-organisms spoil food by:

breaking down its molecules and make new products called (amines) which are generally smelly. This changes its chemical composition as well as its texture and physical appearance.
some microbes secrete poisonous substances called toxins which if consumed lead to food poisoning.
micro-organisms grow in the food and sometimes form a whole colony consisting of such large numbers that this food, if consumed can cause illness. It is called food poisoning.

Question 9.
What are antibiotics ? What precautions must be taken while taking antibiotics ?
Answer:
Antibiotics. These are those chemical secretions which are secreted by certain microorganisms and inhibits the growth of other microorganisms without harming the host.
Alexander Fleming, an English scientist in 1929, discovered Penicillin.
Precautions to be taken while taking antibiotics
Given ahead precautions should be taken while taking antibiotics:

Antibiotics should be taken only on the advice of a qualified doctor,
You must finish the course prescribed by the doctor,
Antibiotics, however, are not effective against cold and flu as they are caused by viruses.

PSEB Solutions for Class 8 Science Microorganisms: Friend and Foe Important Questions and Answers

Multiple Choice Questions

Question 1.
The following slide shows which micro-organism ?
PSEB 8th Class Science Solutions Chapter 2 Microorganisms Friend and Foe 1
(a) Spirogyra
(b) Amoeba
(c) Bacteria
(d) Fungi on bread.
Answer:
(c) Bacteria.

Question 2.
Is of which micro-organism is shown in the diagram ?
PSEB 8th Class Science Solutions Chapter 2 Microorganisms Friend and Foe 2
(a) Spirogyra
(b) Amoeba
(c) Bacteria
(d) Fungi on bread
Answer:
(c) Bacteria

Question 3.
The slide which is being shown below with the help of microscope is of which micro-organism ?
PSEB 8th Class Science Solutions Chapter 2 Microorganisms Friend and Foe 3
(a) Amoeba
(b) Bacteria
(e) Paramecium
(d) Virus
Answer:
(d) Virus.

Question 4.
Which of the following micro-organisms can be seen only with the help of microscope ?
(a) Virus
(b) Bacteria
(c) Yeast
(d) All of the above.
Answer:
(d) All of the above.

Question 5.
Today the teacher in the class showed a slide to his students with the help of microscope. To which micro-organism does this slide belong ?
PSEB 8th Class Science Solutions Chapter 2 Microorganisms Friend and Foe 4
(a) Amoeba
(b) Bacteria
(e) Paramecium
(d) Penciliam
Answer:
(c) Paramecium.

Question 6.
For what purpose yeast is used ?
(a) Sugar
(b) Wine
(c) Hydrocloride Acid
(d) Oxygen
Answer:
(b) Wine

Question 7.
Which of the following is antibiotics ?
(a) Sodium Bicarbonate
(b) Streptomycin
(c) Alcohol
(d) Yeast
Answer:
(b) Streptomycin.

Question 8.
The carrier of malaria-causing protozoan is:
(a) Female anopheles mosquito
(b) Cockroach
(c) Housefly
(d) Butterfly
Answer:
(a) Female anopheles mosquito.

Question 9.
The most common carrier of communicable diseases is:
(a) Ant
(6) Housefly
(c) Dragonfly
(d) Spider.
Answer:
(b) Housefly

Question 10.
The bread or idli dough rises because of:
(a) Heat
(b) Grinding
(c) The growth of yeast cells
(d) Kneeding
Answer:
(c) The growth of yeast cells.

Question 11.
The process of conversion of sugar into alcohol is called:
(a) Nitrogen fixation
(b) Moulding
(c) Fermentation
(d) Infection.
Answer:
(c) Fermentation.

Question 12.
Which instrument is used to see micro-organisms ?
(a) Magnifying glass
(b) Microscope
(c) Telescope
(d) All the above.
Answer:
(b) Microscope.

Question 13.
Which of the following micro-organisms is responsible for causing cholera ?.
(a) Virus
(b) Protozoa
(c) Bacteria
(d) None of these.
Answer:
(c) Bacteria.

Very Short Answer Type Questions

Question 1.
Fill in the blanks:

1. Microorganisms can be seen with the aid of ……………….. .
Answer:
microscope

2. Bacteria normally multiply by ……………….. .
Answer:
binary fission

3. Disease producing microbes are called ……………….. .
Answer:
pathogens

4. The poisonous substances produced by some pathogenic bacteria are known as ……………… .
Answer:
toxins

5. Algae can make their own food because they can ………………… .
Answer:
photo- synthesise

6. The chief source of food for fishes is ……………….. .
Answer:
algae

7. The product of algae used for raising bacterial culture is called ……………….. .
Answer:
agar

8. Algae are plant-like but ……………….. are animal-like.
Answer:
protozoans

9. Mushroom is a type of ………………. .
Answer:
fungus

10. Microorganisms which form the borderline between the living and nonliving world are called …………..
Answer:
viruses

Question 2.
Define microscope.
Answer:
Microscope. It is an optical instrument which enables us to see the very tiny organisms called microorganisms.

Question 3.
Which micro-organism lies on the borderline dividing the living world from the non-living ?
Answer:
Virus lies on the borderline dividing the living and non-living.

Question 4.
Name four antibiotics.
Answer:
Penicillin, Streptomycin, Tetracycline and Gramicidin.

Question 5.
What are micro-organisms ?
Answer:
Micro-organisms. These are small organisms which are too small to be seen with naked eyes.

Question 6.
Name the major groups of micro organisms.
Answer:
The major groups of microorganisms are:
Bacteria, Fungi, Protozoa, Algae and Viruses.

Question 7.
Write the average size of bacterium.
Answer:
1.25 mm (1μm = \(\frac{1}{1000}\) mm) in diameter.

Question 8.
Which is the smallest bacteria ?
Answer:
The smallest is rod-shaped bacteria measuring 0.15 mm.

Question 9.
Name the largest bacteria.
Answer:
Spiral shaped bacteria measuring upto 15 mm in length and 1.5 μm in diameter.

Question 10.
Name two examples of Bacillus.
Answer:
Lactobacillus, Pseudomonas.

Question 11.
Write examples of blue-green algae.
Answer:
Nostoc, Anabaena, Oscillatoria.

Question 12.
How much nitrogen is fixed by blue-green algae in a paddy field in a year ?
Answer:
About 625 kg of nitrogen in one square km area.

Question 13.
Which micro-organism is used in the preparation of bread and alcohol ?
Answer:
Yeast.

Question 14.
Name two nitrogen fixing algae.
Answer:
Nostoc and Anabaena.

Question 15.
What are the two major groups of fungi ?
Answer:
Yeast and moulds.

Question 16.
Under which group of micro-organisms Amoeba fall ?
Answer:
Protozoa.

Question 17.
Name two antibiotics.
Answer:

Streptomycin
Erythromycin.

Question 18.
Who discovered vaccination ?
Answer:
Louis Pasteur.

Question 19.
Name unicellular micro-organism.
Answer:
Bacteria, Protozoa.

Question 20.
Name multicellular micro-organisms.
Answer:
Algae, Fungi.

Question 21.
Name a micro-organism which can live independently.
Answer:
Amoeba.

Question 22.
Name micro-organisms which live in groups.
Answer:
Fungi and Bacteria.

Question 23.
For which purpose antibiotics are used ?
Answer:
Antibiotics are used for curing diseases.

Question 24.
Which micro-organisms are used to prepare antiboitics ?
Answer:
Bacteria and Fungi.

Question 25.
When and who first invented first antiboitic ?
Answer:
Alexander Fleming in 1929, invented first antibiotic.

Short Answer Type Questions

Question 1.
Are all micro-organisms of similar sizes ?
Answer:
No, all micro-organisms are not of similar size. The size of bacteria ranges from 0.2 to 100 microns. The size of yeast ranges from 5 to 10 micron and that of moulds from 2 to 10 micron. The size of algae ranges from 1 micron to several metres in length. The size of protozoa ranges from 2 to 200 microns. The size of viruses ranges from 0.015 to 0.2 micron.

Question 2.
Give examples of a slow and fast growing bacteria.
Answer:
Examples of slow growing bacteria:

Mycobacterium tuberculi
Mycobacterium leprae

Examples of fast growing bacteria:

Pseudomonas
E. coli.

Question 3.
What are the two groups of organisms of fungi ?
Answer:
Fungi consists of two main groups:
Yeasts and Moulds.

Yeasts. They are usually unicellular.
Moulds. They are usually multicellular and have a filament-like appearance.

Question 4.
How do microbes survive adverse conditions ?
Answer:
Micro-organisms are very hardy. They can survive under extreme conditions of temperature and dryness by forming a hard outer coating called a cyst. Within this protective shell, they remain inactive as such, until more favourable conditions return. They, then emerge from their shell, multiply and go through their life cycles.

Question 5.
In what ways, are viruses different from other microbes ? Name two plant viruses and two animal viruses.
Answer:
Viruses are different from other microbes due to the following facts:
1. They are the smallest microbes.
2. They cannot be totally called living beings because they do not grow on their own.
3. They are mostly harmful and cause a number of diseases.

Plant viruses.

Tobacco mosaic virus (TMV)
Bacteriophage.

Animal viruses.

Foot and mouth disease virus (FMDV)
Measle virus.

Question 6.
Why are viruses placed on the border line between living and nonliving things ?
Answer:
Viruses resemble living objects due to following reasons:

They contain nucleic acids.
They grow and multiply like living beings.

Viruses resemble non-living things due to the following reasons:

They do not contain cytoplasm and definite nucleus.
They can be crystallized like salts or sugar.

Question 7.
Differentiate between yeasts and moulds.
Answer:
Differences between Yeasts and Moulds

Yeasts	Moulds
1. They are unicellular.	1. They are multi-cellular.
2. They range in size from 5-10 microns.	2. They range in size from 2-10 microns.
3. Yeasts are both aerobic as well as anaerobic.	3. Moulds are aerobic.

Question 8.
Write some examples of commercial products obtained from fungi.
Answer:

Some fungi are directly used in the preparation of dishes.
Some antibiotics are obtained from fungus.
Some fungi are used in the preparation of bread and alcohol.
Wines, beers are prepared with the help of certain fungi.

Question 9.
What are Bacteriophages ?
Answer:
Bacteriophage. Viruses are heterotrophic. Virus which depend on bacteria are called bacterial viruses or bacteriophages.
It is shaped like a rod. They destroy bacteria which are responsible for spoilage of organic matter.
PSEB 8th Class Science Solutions Chapter 2 Microorganisms Friend and Foe 5

Question 10.
Describe the various products involving action of fungi.
Answer:
The various products involved are as follows:

Bakery products. Bread and cakes from wheat flour.
Food products. Wines, beers from fruit juices or barley ; idli and dosa from a mixture of powdered rice and dal.
Processed cheese.
Some fungi such as mushrooms are directly used as food products.
Some very important medicines, such as penicillin are made from fungi.
Moulds spoil food, damage potato and crop plants, corn and wheat. They also cause rotting of clothes, shoes and wooden materials.
Some fungi cause diseases like athlete’s foot and ringworm.

Question 11.
How is bread formed ?
Answer:
When yeast together with some sugar and warm water is mixed with flour (atta or maida), the dough begins to rise. The presence of sugar and the warmth stimulates rapid growth of the yeast cells. During their reproduction, yeast cells produce carbon dioxide. Bubbles of CO₂ fill the dough and make it rise. When baked into a loaf, the bread becomes light and spongy.

Question 12.
How is the mixture of ground rice and dal made sour ?
Answer:
The mixture of ground rice and dal is allowed to stand for a few hours. It becomes sour. It is the growth of yeast cells that causes the mixture to rise and become sour.

Question 13.
Suggest some methods to prevent the growth of moulds.
Answer:

Keep the things at low temperatures.
Keep the things in clean closed containers.
Keep the things in dry condition in dry storage.
Keep the food in the form of syrups, pickles, in the form of preserved food.
Keep the articles away from the reach of microorganisms present in the air.

Question 14.
Write the importance of fungi in medicines.
Answer:
Antibiotics are obtained from fungi, and Penicillin is obtained from the fungus, Griscofulvin is extracted from the fungus Griscofulvum.

Question 15.
What are the major differences between algae and fungi ?
Answer:

Algae	Fungi
1. Green in colour.	1. Colourless or non-green.
2. Outer cell wall is formed by cellulose.	2. Outer cell is formed of fungus cellulose.
3. Autotrophic.	4. Saprophytic or Parasitic.
4. Aquatic in habitat.	3. Heterotrophic.
5. Grow on wet surfaces.	5. Grow on moist organic surface.

Question 16.
What are vaccines ?
Answer:
Vaccines.
A vaccine consists of antigens of mild strains of pathogens of a specific disease. When injected into the blood stream, it stimulates while blood cells to produce antibodies.

Question 17.
Describe the role of blue green algae in the fertility of soil.
Answer:
Blue green algae play an important role in the fertility of soil due to the following reasons:

They make the nitrogen available to the soil.
They increase the humus content of the soil.
They support the crop growth.
They improve the water holding capacity of the soil.

Question 18.
Describe some of the important landmarks in the study of microorganisms.
Answer:
Important landmarks in the study of microorganisms are as follows:

Name of the scientist	Year	Contribution
Robert Hooke	1665	Observed cork cells, spermatozoa and bacteria using a simple microscope and named them as tiny animalcules.
Louis Pasteur	1857 1859	Fermentation is a biochemical process. Microbes produce only from pre-existing microbes of same species.
Robert Koch	1872	Tubercle bacillus is the main cause of tuberculosis germ theory of disease.
Shikabasaburo Alexander Fleming	1889 1929	Tetanus disease is due to Tetanus bacillus. Antibiotic penicillin from Penicillium notatum (a fungus).

Question 19.
What is food poisoning ?
Answer:
Food Poisoning. Sometimes the microorganisms grow on our food items and spoil it. When we eat this food, it causes food poisoning. It causes serious illness and even death.

Question 20.
Explain the following terms in brief:
(a) Immunity
(b) Antibodies
(c) Vaccination.
Answer:
(a) Immunity.
Immunity is the ability of a person (or organism) to resist the development of a disease even when infective dose of the pathogen has been introduced. The science of development of resistance or defence to the causative agents of the diseases is termed as immunology. Foundations of immunology were laid by Edward Jenner (1796) who successfully developed first vaccine against small pox.

(b) Antibodies.
It is a substance occurring naturally in the blood or produced in response to the presence of antigen which is able to overcome the toxic effect of an antigen.

(c) Vaccination.
It is a process of injecting a substance (Vaccine) into a healthy person in order to develop immunity against a specific disease.

Question 21.
Write three ways of entering microorgnisms into the body.
Answer:
Entry of microorganisms into the body

Through the air we inhale.
Through the water we drink, and the food we eat.
Through skin.

Question 22.
What is vaccine ? Describe the importance of vaccination.
Answer:
Vaccine. A vaccine consists of a small amount of dead or weakened germs of a particular disease that are injected into the body. Injecting or swallowing a vaccine is called the vaccination when the vaccine is injected into our body. Our body produces antibodies that fight with those dead or weakened germs. These antibodies stay in our body to prevent the future attack of such kind of microbes. Thus, our body develops immunity against the particular disease for which vaccination is provided.

Question 23.
Write a note on cyanobacterial cell.
Answer:
PSEB 8th Class Science Solutions Chapter 2 Microorganisms Friend and Foe 6
Cyanobacteria.
These are chlorophyll containing autotrophic microscopic bacteria, also called blue green algae. They may be filamentous or colonial in form. Main examples are Oscillatoria, Spirulina, Nostoc, Stigonema.

A typical cyanobacterial cell consists of a four layered cell-wall followed by plasma membrane. The cytoplasm contains gas vacuoles, ribosomes photosynthetic pigments such as chlorophyll a, carotenoids and circular double stranded naked DNA. The reserve food is in the form of cyanophycean starch, liquid globules and cyanophycean protein granules.

Question 24.
What are diatoms ? Sketch a few examples of diatoms.
Answer:
Diatoms.
They are microscopic unicellular algae found in fresh water springs, estuaries and marine water of ocean. They occur mostly as individual cells and some form colonies. Diatoms deposit silicon dioxide in their cell wall. They reproduce asexually as well sexually.
Examples of Diatoms
PSEB 8th Class Science Solutions Chapter 2 Microorganisms Friend and Foe 7

Question 25.
Ajit kneaded 1/2 kg maida along with lukewarm water. He also added some sugar and yeast in it. What will be the effect on kneaded flour after 2 hours ? Give reason for your answer.
PSEB 8th Class Science Solutions Chapter 2 Microorganisms Friend and Foe 8
Answer:
The dough begins to rise. The presence of sugar and yeast stimulates rapid growh of the yeast cells. During their reproduction, yeast cells produce carbon dioxide. Bubbles of CO₂ fill the dough and make it rise.

Long Answer Type Questions

Question 1.
Sketch few of the micro-organisms.
Answer:
PSEB 8th Class Science Solutions Chapter 2 Microorganisms Friend and Foe 9

PSEB 8th Class Science Solutions Chapter 2 Microorganisms Friend and Foe 11

Question 2.
Give in a tabulated form some of the common diseases affecting man and their mode of transmission and methods of prevention.
Answer:
Some Common Human Diseases Caused by Micro-organisms:
PSEB 8th Class Science Solutions Chapter 2 Microorganisms Friend and Foe 12

Question 3.
Give some of the common plant diseases caused by micro-organisms.
Answer:
Common Plant Diseases Caused by Micro-organisms

Plant Diseases	Micro-organism	Mode of Transmission
Citrus canker	Bacteria	Air
Rust of wheat	Fungi	Insects and seeds
Yellow vein mosaic of Ladyfinger	Virus	Insect

Question 4.
What is meant by food preservation? Explain the different methods of food preservation used for foods.
Answer:
Food Preservation. The processes by which the perishable food materials are treated to prevent their spoilage and retain their nutritive value for long periods
is called food preservation.
The substances used for food preservation are called food preservatives.
Different Methods of Food Preservation:

1. Dehydration and Sun Drying.
The process of removal of water from fruits, vegetables is called dehydration. It reduces the moisture content of food materials and, therefore, prevents the food from spoilage. Drying in the sun is one of the oldest methods of food preservation.

2. Preservation by Salt and Sugar.
Common salt and sugar are good preservatives. These stop the bacterial growth in the food material. Pickles, jam, jelly, ketchup, squash, etc. are preserved by adding salt and sugar.

3. Deep Freezing. It is a direct method for the prevention of bacterial growth. In this method, the food materials are cooled below 0 C. Fruits vegetables, meat, fish, etc. can be easily preserved by this method.

4. Chemical Preservation. Certain chemicals can be used to preserve food. The substances which are added to the food materials to prevent their spoilage are called food preservatives. Benzoic acid, Potassium metabisulphite, etc. can be used. Irradiation, canning, and bottling are also used for the preservation of food.

PSEB 8th Class Science Solutions Chapter 5 Coal and Petroleum

September 26, 2024September 25, 2024 by Prasanna

Punjab State Board PSEB 8th Class Science Book Solutions Chapter 5 Coal and Petroleum Textbook Exercise Questions and Answers.

PSEB Solutions for Class 8 Science Chapter 5 Coal and Petroleum

PSEB 8th Class Science Guide Coal and Petroleum Textbook Questions and Answers

Exercises

Question 1.
What are the advantages of using CNG and LPG as fuels?
Answer:
Advantages of LPG:

LPG is considered to be a better fuel because of the following reasons:

LPG has a high calorific value. Its calorific value is about 50 kJ/g. This means that when 1 gram of LPG burns in a gas stove, it produces about 50 kilo-joules of heat energy.
It burns with a smokeless flame and so does not cause pollution.
LPG does not produce any poisonous gases on burning.
LPG is easy to handle and convenient to store.
It undergoes complete combustion.
LPG is a very neat and clean domestic fuel.

Advantage of CNG:
It does not cause air pollution.

Question 2.
Name the petroleum product used for surfacing of roads.
Answer:
Bitumen.

Question 3.
Describe how coal is formed from dead vegetation. What is this process called ?
Answer:
Formation of coal from dead vegetation:
About 300 million years ago, the forests got buried under the soil. They were compressed by soil deposits and temperature also rose as they sank deeper and deeper. Due to this high temperature and pressure coal was formed from dead vegetation by process of carbonisation.

Question 4.
Fill in the blanks.
(a) Fossil fuels are …………….. , …………… and ……………
(b) Process of separation of different constituents from petroleum is called ………………… .
(c) Least polluting fuel for vehicle is ………………..
Answer:
(a) Coal, petroleum, natural gas.
(b) refining.
(c) CNG (Compressed natural gas).

Question 5.
Tick True/False against the following statements.
(a) Fossil fuels can be made in the laboratory.
Answer:
False

(b) CNG is more polluting fuel than petrol.
Answer:
False

(d) Coal tar is a mixture of various substances.
Answer:
True

(e) Kerosene is not a fossil fuel.
Answer:
True

Question 6.
Explain why fossil fuels are exhaustible natural resources.
Answer:
Fossil fuels are formed from remains of dead organisms and it took million of years to get these organisms converted into fuels. The known reserves of these fuels are limited and so, these are exhaustible fuels.

Question 7.
Describe the characteristics and uses of coke.
Answer:
Characteristics of Coke:

It is tough, porous and black substance.
It is pure form of carbon.

Uses of Coke:

It is used to manufacture artificial graphite.
It is used in manufacture of calcium carbide required for manufacture of acetylene gas. Acetylene gas is the basic raw material for manufacture of acetic acid and P.V.C.
It is used in manufacture of water gas and producer gas used as an important fuel.
- Water gas is not single gas. It is a mixture of equal volumes of carbon monoxide and hydrogen.
- Producer gas is produced by passing controlled amount of air over red hot coke. Producer gas is in fact a mixture of one part of carbon monoxide and two parts of nitrogen by volume.
It is used to extract metals like copper, iron, zinc, lead, tin etc., from their ores.
Since coke does not produce any smoke, hence it is used as a household fuel.

Question 8.
Explain the process of the formation of petroleum.
Answer:
Formation of Petroleum.
Petroleum is formed from the bacterial decomposition of the remains of animals and plants which got buried under the sea millions of years ago. When these organisms died, they sank to the bottom and got covered by sand and clay. Over a period of millions of years, these remains got converted into petroleum oil by heat, pressure and catalytic action. The hydrocarbons formed rose through porous rocks until they were trapped by impervious rocks forming an oil trap. Natural gas is found above the surface of petroleum oil.

Question 9.
The following table shows the total power shortage in India from 1991-1997. Show the data in the form of a graph. Plot shortage percentage for the years on the Y-axis and the year on the X-axis.

S. No.	Year	Shortage %
1	1991	7.9
2	1992	7.8
3	1993	8.3
4	1994	7.4
5	1995	7.1
6	1996	9.2
7	1997	11.5

Answer:
PSEB 8th Class Science Solutions Chapter 5 Coal and Petroleum 1

PSEB Solutions for Class 8 Science Coal and Petroleum Important Questions and Answers

Multiple Choice Questions

Question 1.
Gurmeet’s mother uses cylinder to cook chapatti on gas burner at home. Name the gas in cylinder.
(a) Air
(b) Oxygen
(c) L.P.G.
(d) C.N.G.
Answer:
(c) L.P.G.

Question 2.
Monika read in a newspaper that a man became unconscious because of burning coal in a closed room. The teacher told her that during burning coal, a gas is produced which causes death of a person. Name
this gas.
(a) Oxygen
(b) Nitrogen
(c) Carbon-monoxide
(d) Hydrogen.
Answer:
(c) Carbon-monoxide.

Question 3.
The example of fossil fuel is:
(a) Air
(b) Sunlight
(c) Water
(d) Coal
Answer:
(d) Coal

Question 4.
Which out of the following is used as fuel in households ?
(a) Diesel
(b) Petrol
(c) Kerosene oil
(d) Bitumen.
Answer:
(c) Kerosene oil.

Question 5.
The purest form of carbon is:
(a) Coaltar
(b) Coal gas
(c) Diamond
(d) None of the above.
Answer:
(c) Diamond.

Question 6.
Which out of the following is the least pollution causing fuel ?
(a) Petrol
(b) Coal
(c) Kerosene oil
(d) C.N.G.
Answer:
(d) C.N.G.

Question 7.
Which is the natural solid fuel ?
(a) Coal
(b) Coke
(c) L.P.G.
(d) Coal tar
Answer:
(a) Coal.

Question 8.
Which among the following is the best domestic fuel ?
(a) Petrol
(b) Coal
(c) Kerosene oil
(d) C.N.G.
Answer:
(d) C.N.G.

Question 9.
Which of the following is the fossil fuel ?
(a) Air
(b) Hydrogen gas
(c) Water
(d) Coal.
Answer:
(d) Coal.

Question 10.
Which out of the following is the non renewable source of energy ?
(a) Air
(b) Sunlight
(c) Coal
(d) Forests
Answer:
(c) Coal

Question 11.
Which out of the following is called black gold ?
(a) Diesel
(b) Coal
(c) Bitumen
(d) Petroleum.
Answer:
(d) Petroleum.

Question 12.
Which out of the following is limited natural resource ?
(a) Air
(b) Sunlight
(c) Natural gas
(d) None of the above.
Answer:
(c) Natural gas.

Very Short Answer Type Questions

Question 1.
Name some natural materials.
Answer:
Air, water, soil, forests, minerals etc.

Question 2.
Name some man-made materials.
Answer:
Glass, cement, clothes, houses etc.

Question 3.
Define the term fossil fuel. Name three fossil fuels.
Answer:
Fossil fuels.
These are the fuels which are formed in nature from the dead remains of organisms over millions of years ago.
Examples. Coal, natural gas, petroleum etc.

Question 4.
How is coke prepared ?
Answer:
Coke is prepared by the destructive distillation of coal. The gases, and other substances present in coal are given off on heating. The black residue left behind is coke.

Question 5.
Name two products formed by Destructive distillation of Coal.
Answer:

Coal gas
Coal tar.

Question 6.
Name some products formed as a result of Fractional distillation of Petroleum.
Answer:
Asphalt, petrol, diesel oil, paraffin wax, fuel oil, kerosene oil.

Question 7.
Name three products of petroleum.
Answer:
Fertilizer, Insecticide, Artificial rubber.

Question 8.
What will happen if fossil fuels are used up at a fast rate ? Give reasons.
Answer:
Fossil fuel will get exhausted because the earth cannot recreate them rapidly.

Question 9.
Coal, petroleum, natural gas are example of which type of fuel ?
Answer:
Fossil fuel.

Question 10.
What is petroleum ?
Answer:
Petroleum. Petroleum is thick viscous crude oil with an unpleasant odour.

Question 11.
Which type of rocks store petroleum in them ?
Answer:
Impervious (non-porous) rocks.

Question 12.
Which process is used for refining petroleum ?
Answer:
Fractional distillation.

Question 13.
How is petroleum gas produced ?
Answer:
It is produced in the form of uncondensed gas during fractional distillation of crude petroleum oil.

Question 14.
What is the use of bitumen ?
Answer:
Road surfacing.

Question 15.
Which liquid fuel is used in stoves, lamps and jet air-crafts ?
Answer:
Kerosene oil.

Question 16.
Which product of petroleum is used for dry cleaning ?
Answer:
Petrol.

Question 17.
Name few exhaustible natural resources.
Answer:
Forests, wild life, minerals, coal etc.

Question 18.
Give examples of in-exhaustible natural resources.
Answer:
Air, water, sunlight etc.

Question 19.
Which natural material is available at a blacksmith’s place ?
Answer:
Coal.

Question 20.
What is main component of coal ?
Answer:
Carbon.

Question 21.
Which process converts dead vegetation into coal ?
Answer:
Carbonisation.

Question 22.
What happens when coal is heated or burn in air ?
Answer:
Carbondioxide gas is released.

Question 23.
Which condition is necessary for destructive distillation ?
Answer:
Absence of oxygen.

Question 24.
What is the latest use of coal-gas ?
Answer:
As a source of heat energy.

Question 25.
What is destructive distillation ?
Answer:
Destructive Distillation – The process of heating coal in the absence or limited supply of air is called destructive distillation.

Question 26.
What are hydrocarbons ?
Answer:
Hydrocarbons. The compounds of carbon and hydrogen are called Hydrocarbons.

Question 27.
What are Petrochemicals ?
Answer:
Petrochemicals.
These are the substances obtained from Petrol and Natural gas. These are largely used for the manufacture of detergents, synthetic fibres and plastics etc.

Short Answer Type Questions

Question 1.
Write two differences between Exhaustible and In-exhaustible Resources.
Answer:
Differences between Exhaustible and In-exhaustible Natural Resources.

Exhaustible Natural Resources

In-exhaustible Natural Resources

1. Limited quantity in nature.

1. Limitless or unlimited quantity in nature.

2. Gets exhausted on consumption.

Examples: Forests, wild life.

2. Cannot exhaust on consumption i.e. can be retrieved back.

Examples: Air, Sun energy.

Question 2.
Where is petroleum found in India ?
Answer:
In India, petroleum is found in the states of Gujarat and Assam. It is also obtained from reservoirs buried deep under the sea bed near Mumbai. This oil-bearing region is called Bombay-High. Recently, oil has also been discovered in Godavari and Kaveri basins.

Question 3.
What are the major products of Petroleum refining ?
Answer:
During refining of petroleum following fractions are produced:

Natural gas, Petrol,
Naphtha,
Kerosene oil,
Gas oil (diesel),
Lubricating oil/waxes,
Fuel oil and
Bitumen.

Question 4.
What are the products of coal ?
Answer:
Coal on heating in the absence of air gives coal gas, coal tar, and coke. Coal gas is also a good fuel. Coal tar gives important chemicals such as benzene, toluene, naphthalene, anthracene etc.

Question 5.
What is coal gas ? How is it formed ? Give its uses.
Answer:
Coal Gas. Coal gas is a mixture of methane, hydrogen and carbon monoxide.
When coal is heated in the absence of air, coal gas is formed.
Uses.

It is used as a fuel.
It is used for providing reducing atmosphere in metallurgical operations.

Question 6.
Give few uses of coal.
Answer:
Uses of Coal:

As a fuel to cook food.
To produce steam to run an engine.
To produce electricity in Thermal Power plants.
As a fuel in industry.

Question 7.
What is coal tar ? What are its uses ?
Answer:
Coal Tar. Coal tar is a black thick liquid with unpleasant smell. It is a mixture of about 200 substances, which are used as starting materials for the manufacturing of various daily need ithins such as paints, dyes, plastics, films, perfumes, explosives, drugs etc.
Coal tar is also used for road surfacing.

Question 8.
Name at least three constituents of petroleum and give their uses.
Answer:
Constituents of Petroleum

Petrol
Paraffin wax
Diesel.

Uses of Petroleum:

Petrol is used as a motor fuel and aviation fuel. It is also used for dry cleaning.
Paraffin wax is used for making ointments, candles, vaseline etc.
Diesel is used as a fuel for heavy motor vehicles and electric generators.

Question 9.
Define natural resource.
Answer:
Natural Resource. The resource that is obtained from nature is called natural resource.

Question 10.
What are the characteristics of a good fuel ?
Answer:
Characteristics of Good Fuel:

It should be easily available.
It should be cheap.
It should be clean and should not produce poisonous gases and ash after burning.
It should produce more energy.
It should be easy to transport and store.

Question 11.
What is the difference between coal and coke ?
Answer:
Differences between Coal and Coke

Coal	Coke
1. It is a non-crystalline form of carbon	1. It is an amorphous form of carbon.
2. It is obtained bj? death and decay of plants which remain buried under the earth for years together.	2. It is obtained by heating soft coal in the absence or limited siuply of air.

Long Answer Type Questions

Question 1.
What are fossil fuels ? How are they formed ? Why are they called non¬renewable sources of energy ?
Answer:
Petroleum, natural gas, coal etc., are main forms of fossil fuels. Millions of years ago, remains of animals, plants got buried under the earth before dinosaurs. These remains are called fossils. They remained inside the earth under huge pressure and high temperature in the absence of oxygen, these remains got converted into fossil fuel.

Fossils as a source of non-renewable source of energy.
Fossils were formed several hundred years ago under the earth. Man uses these for his various activities. These cannot be regained after use. So they are called non-renewable source of energy.

Question 2.
Describe the formation of
(a) Coal
(b) Petroleum.
Answer:
(a) Coal Formation.
Coal is believed to be formed from fossils which got buried inside the earth during earthquakes, volcanic eruptions etc., which occurred about 300 million years ago. These fossils were covered with sand, clay and water. In the absence of air and under high temperature and high pressure inside the earth, the fossils got converted into coal. This process of conversion of plants and animals buried inside the earth under high temperature and pressure to coal is called carbonisation. It is a very slow process and may have taken thousands of years.

(b) Formation of Petroleum.
It is believed that petroleum was formed and preserved in its crude state in the earth from the remains of dead microscopic marine plants (phytoplankton) which settled in muddy sediments at the bottom of sea millions of years ago. Prolonged sedimentation and cooking of these organic debris under pressure in the presence of natural catalysts, converted them into petroleum . For this reason, petroleum is also called fossil fuel.
PSEB 8th Class Science Solutions Chapter 5 Coal and Petroleum 2

Question 3.
What is petroleum? How does it occur? How is it mined?
Answer:
Petroleum.
It is dark coloured viscous, foul-smelling, oily liquid. It is a complex mixture of several solid, liquid, and gaseous hydrocarbons mixed with water, salt, and earth particles.

Occurrence of Petroleum.
Petroleum occurs deep down under the earth between two impervious rocks (non-porous rocks) as shown in Fig. Natural gas occurs above the petroleum oil trapped under rocks.

The crude petroleum is obtained by drilling a hole into the earth’s crust and sinking pipes into it. When the pipe reaches the oil deposit, natural gas comes out with great pressure. After the pressure has subsided, the crude oil is pumped out of the oil well. This process of obtaining crude oil from its sources is called mining.

PSEB 8th Class Social Science Solutions Chapter 4 Our Agriculture

September 26, 2024September 25, 2024 by Bhagya

Punjab State Board PSEB 8th Class Social Science Book Solutions Geography Chapter 4 Our Agriculture Textbook Exercise Questions and Answers.

PSEB Solutions for Class 8 Social Science Geography Chapter 4 Our Agriculture

SST Guide for Class 8 PSEB Our Agriculture Textbook Questions and Answers

I. Answer the following questions in 1-15 words:

Question 1.
What do you understand by Agriculture?
Answer:
Agriculture includes raising crops, cattle rearing, and other agricultural activities. It also includes dairy farming, poultry, bee-hiving, fishing, floriculture, gur production, flour mills, etc.

Question 2.
Which factors affect Agriculture?
Answer:
The following factors affect agriculture:

Climate
Relief
Type of soil
Irrigation
Method of cultivation
Marketing
Means of transportation and
Banking facilities.

Question 3.
Write a brief note on plantation farming.
Answer:
It includes the cultivation of single crop on large farms.

Question 4.
Write the names of cereal crops.
Answer:
Main cereal crops are Rice, Wheat, Maize, Jowar, Bajra, Pulses and Oilseeds.

Question 5.
What is puddling?
Answer:
For rice cultivation, seeds are planted in the fields. The field is levelled and filled with water. This is called puddling the field where rice plants are transplanted.

Question 6.
What products are prepared from Maize?
Answer:
Glucose, starch, alcohol and vegetable oil is prepared from Maize.

Question 7.
How many types of cotton are there on the basis of the length of staple?
Answer:

Long staple cotton (Best Type)
Medium staple cotton
Short staple cotton.

Question 8.
Which are the things that can be made from jute?
Answer:
Bags, ropes, strings, etc. and shoes are prepared from jute.

Question 9.
How does the tea plant look like?
Answer:
Tea plant is a bush. Its leaves provide tea.

Question 10.
Write the names of three types of coffee.
Answer:

Arabica
Robusta
Liberica.

Question 11.
What is the percentage of people engaged in agriculture in U.S.A. and Punjab?
Answer:

U.S.A.-More than 30% people
Punjab-58% people.

II. Answer the following questions in 50-60 words :

Question 1.
After writing the types of Agriculture differentiate between intensive and extensive agriculture.
Answer:
Types of Agriculture :

Sedentary Agriculture
Shifting Agriculture
Dry Farming
Wet Farming
Intensive Farming
Extensive Farming
Mixed Farming
Horticulture
Individual Agriculture
Co-operative Farming
Collective Farming
Plantation Agriculture
Subsistence Agriculture
Commercial Farming.

The distinction between Intensive and Extensive Farming :

Intensive farming is done on small farms while extensive farming is done on large farms.
Irrigation and fertilizers are used in intensive farming while machines are used in extensive farming.
Intensive farming is done in Punjab while extensive farming is done in U.S.A.

Question 2.
Differentiate between subsistence and commercial type of farming.
Answer:
1. Subsistence Farming: Majority of farmers in the country practise subsistence farming. It is characterised by small and scattered land-holdings and use of primitive tools. As the farmers are poor, they do not use fertilisers and high yielding variety of seeds in their fields to the extent they should do. These result into low productivity. Important cash crops like sugarcane, oilseeds, cotton and jute are grown. The subsistence agriculture has given way to commercial agriculture to some extent.

2. Extensive Farming: Extensive farming is bush or tree farming. It is a single crop farming of rubber, tea, coffee, cocoa, spices, coconut and fruit crops. It is capital-intensive and demands good managerial ability, technical know-how, sophisticated machinery, fertilisers, irrigation and transport facilities. Extensive farming is done in U.S.A. and Canada.

Question 3.
Which are main Rice producing areas?
Answer:
Cultivation of Rice. Rice is grown in deltas, flood-plains, coastal-plains and some terraced fields in the mountainous areas as well. It is one of the crops for which a lot of human labour is required. All operations including the preparation of seedling beds, ploughing, planting, weeding, harvesting and separation of grain are done by human labour.

Rice requires high temperature of over 20°C to germinate, bloom and mature. Rainfall of 100 cm to 150 cm is required. Paddy is cultivated mainly in India, China, Japan, Bangladesh, Indonesia, Thailand and Myanmar.

In India rice is cultivated most widely in Uttar Pradesh, West Bengal and Andhra Pradesh. Other producers are Assam, Tamil Nadu, Orissa and Punjab.

In Punjab, rice is grown in districts of Amritsar, Gurdaspur, Ferozepur, Jalandhar, Patiala and Ludhiana.

Question 4.
Explain the conditions required for cultivation of cotton and jute.
Answer:
Cotton. Cotton requires cloud free sunny days and uniformly high temperature. It grows best in areas where the temperature is between 30°C to. 40°C. Cotton plants require rainfall of 60 to 100 cm. Alluvial and black soils are best suited for cotton plants.

Jute. Jute fibre is obtained from the bark of the jute plant stem.
The jute plant originated in the Indian subcontinent. It grows best in well drained sandy loam and requires warm and humid climate. Jute plant requires temperature of more than 25°C and rainfall of over 150 cm per year.

Question 5.
Write a note on cotton production in Punjab.
Answer:
Punjab and Haryana together produce 25% cotton of India. The major producers are Ferozepur and Sangrur districts. B.T. cotton has been successfully grown in Punjab. Malwa region is also called white gold.

Question 6.
Write about protection of tea and coffee plants.
Answer:
Tea. Tea plants are planted on cleared slope. So that on well drained slopes, water should not stand in the roots of plants. Fertilizers are used for growth of tea plants. Tea plant needs pruning for its proper growth.

Coffee. Coffee saplings are grown in Nursery and then transplanted in the fields. The plants require use of fertilizers, pruning, and irrigation. Sunny weather is required during growth. The tree is pruned to keep it upto a height of 8 feet.

Question 7.
Write a note on the uses of machines in agricultural operations in U.SA.
Answer:
Two types of farms are functioning in the United States viz.,

specialized farms and
mixed farms.

A specialized farm concentrates on a particular type of crop or livestock, whereas a mixed farm raises a variety of crops. About 95 per cent of farms in the USA are specialized farms. Mostly cereal grains such as corn, wheat, sorghum, rice, barley, oats and rye are grown in specialized farms. However, specialized farms also produce crops such as cotton, groundnut, sugarcane, tobacco, vegetables and fruits. Nearly half the specialized farms in the USA are livestock farms. These livestock farms rear meat animals, raise milk cows, chickens and turkeys. In the mixed farms, farmers produce a variety of crops and rear livestock. The United States is the world’s leader in international agricultural goods market.

III. Answer the following questions in about 125-130 words :

Question 1.
After writing about conditions for the growth of wheat explain the areas of wheat production. (P.B. 2009)
Answer:
Geographical conditions of growth. Wheat needs a cool and wet climate during growing season and a warm dry climate during harvesting season. It requires a rainfall of 50 cm to 75 cm. It is a rabi crop. It grows best in winter due to winter rainfall and regular irrigation. It does not depend on destiny like rice crop. Wheat grows best on loamy soils. Mechanisation and use of chemical fertilizers give higher yields.

Production. Wheat is one of the oldest cereal crops cultivated in the world. Wheat is grown in temperate regions with rainfall ranging between 30 cm to 80 cm.

Three countries: the United States of America, Russia and China are the major producers of wheat. The world’s largest producer is China. Other leading producers are India, Ukraine, France, Canada, Pakistan and Argentina. Winter wheat and spring wheat belts of USA and Canada are quite famous.

Wheat cultivation is mainly carried on in fertile soils or loamy soils. Different climatic conditions and sowing seasons across the world have led to harvesting of wheat in every month of the year in one or the other part of the world. It is grown in Punjab, Haryana, Uttar Pradesh, Madhya Pradesh, Maharashtra and Bihar. India is the second largest producer of wheat in the world. The production and yield in Punjab has increased due to Green Revolution, Better seeds, fertilizers and irrigation is used. ,

Question 2.
What are the conditions required for the growth of Tea and Coffee? Explain the main areas of tea and coffee production in India.
Answer:
Geographical Conditions of Growth of Tea. Tea is a plant of both tropical and temperate areas.

Temperature. Tea requires uniformly high temperatures (20° – 30°C) throughout the year. Frost is harmful for tea leaves.
Rainfall. An annual rainfall of 150 cm is essential for the growth of tea.
Soil. Tea requires a deep acidic and fertile soil.
Land. Tea is grown on gently sloping, well drained hill slopes and valley-sides.
Labour. Tea is a labour intensive crop. It requires cheap, skilled labour for picking tea-leaves.

Conditions for Growth of Coffee. One-third of the world population drinks coffee, the second largest beverage after tea. There are two types of coffee plants. Coffee Arabica or Mocha and Coffee Robusta. Robusta is the main variety produced in the world.

The coffee plant requires warm climate and moderate rainfall. Both strong sunshine and snowfall are harmful to the plant. During its growth, coffee plant requires rainfall of 100 cm to 150 cm and temperatures between 15°C and 25°C. Irrigation is required where the annual rainfall is less than 100 cm.

Areas of Cultivation of Tea. More tea is produced in Northern India than Southern India. Tea is grown on an area of 4.21 lakh hectares.

The average yield is 1540 kg per hectare. Assam produces about 50% tea of India.
1. Assam. Assam is the largest producer of tea in India. Tea is grown on the valley sides of Brahmaputra and Duar region.

2. West Bengal. Tea is grown in Darjeeling and Jalpaiguri districts in West Bengal. Darjeeling tea has a special flavour. This flavour is due to slow growth under high humidity and low temperature.

3. Southern India. Tea is grown on the slopes of Nilgiris, Cardamom and Anamalai hills, Coimbatore (Tamil Nadu), Malabar coast (Kerala), Coorg region (Karnataka) and Ratnagiri (Maharashtra) are important areas of tea production. Areas of Cultivation of Coffee.

Karnataka is the largest coffee producing state of India.
(а) Karnataka. Coffee is grown in the districts of Chikamanglur, Coorg, Hassan, Shimoga (Nilgiris) in Karnataka state. High rainfall, sunshine, protected slopes, well- drained soils favour the cultivation of coffee.
(b) Arcot, Tinevelley, Madurai, Coimbatore districts of Tamil Nadu grow coffee.
(c) In Kerala, Cardamom hills covering the districts of Palghat and Thiruvananthapuram.

Question 3.
Write down the process involved in Jute production. Write in detail the uses and distribution of Jute in the world.
Answer:
Jute: Jute is an industrial fibre. It is the cheapest fibre. It has commercial importance. It is also called ‘golden fibre’. It is used in the making of carpets, ropes, covers and linoleum. It is used for packing many agricultural commodities. Jute is called ‘Brown Paper of Whole-sale trade’. Jute fibre has softness, strength and length.

Conditions of Growth: Jute is a plant of hot-wet tropical areas.

Temperature. It requires uniformly high temperature (27°C) throughout the year.
Rainfall. Jute requires well distributed heavy rainfall (150 cm).
Soil. It is grown on flood plains and deltas. Fertilizers are also used.
Clean Water. Jute needs an ample supply of clean water for washing.

Area and Production: The jute is grown on an area of about 8 lakh hectares. The total production is about 93 lakh bales (each bale = 180 kg). The average yield is 2014 kg per hectare.

India is the largest producer of jute in the world. Due to partition of India 75% of jute producing areas remained in East Pakistan (now Bangladesh). There was shortage of raw jute for jute mills in India. Now India is self-sufficient in jute production. Coarse jute called Mesta is also grown.

Areas of Cultivation

West Bengal. West Bengal is the largest producer of jute in India. Jute is grown in Ganges delta. Murshidabad, Burdwan, Nadiad, Hooghly are the main jute producing districts.
Assam. Jute is grown in Goalpara, Kamrup and Tezpur districts in Brahmaputra valley.
Bihar. Jute is grown in Terai districts of Purnea and Champaran. The major producers of Jute in the world are China, India, Bangladesh, Thailand and Brazil.

Question 4.
What are the similarities and variations in the agriculture of Punjab and the U.S.A.?
Answer:
(A) Agriculture in the U.S.A.-A Glance :

Agriculturally, the U.S.A. is a developed country. About 3% of the total population is engaged in agriculture,
The main reason behind this is that all the activities of agriculture are carried on by machines and. not by men.
Agricultural activities are carried on about 20% part of the land,
The main agricultural areas include North-West, North-East, interior plains and coastal plains of the country. Different types of crops are grown in different parts of the country,
The farmers of the U.S.A. have large landholdings as compared to that of India. The farm size is very big. The average farm size in U.S.A. is 700 acres. Due to the large size of the fields, extensive type of agriculture is practised.
Machines are used at a very large scale. It is almost impossible to work in farms without machines,
In a farm, only one type of crop is cultivated. From the sowing of crop to the taking of the crop to markets or stores, every work is done with the help of machines,
Insecticides and pesticides are properly utilized. The farmer of U.S.A. practice agriculture like a businessman and not like a mere farmer.

(B) Agriculture in Punjab (India)-A Glance :

Punjab in comparison to other states of India, is much advanced in agriculture. The agriculture sector contributes 35% to the total income of the country. About 58% population of the state is engaged in agriculture,
The soils here are fertile in nature. To maintain the fertility of the soils, the farmer also uses fertilisers,
The farmers of Punjab do not have too much of land. Landholding mostly range between 5 to 25 acres. Some farmers possess even less land. Six percent farmers of the state have more than 25 acres of land.
The farmer grows, different types of crops in his fields. The variations in crops mainly depend on climate, size of landholding, type of soil, irrigation facilities and requirements of the farmer.
According to the size of the land holding the farmer uses tractor or combine harvester,
Almost all the net sown area comes under irrigation. The farmer of Punjab also uses insecticides and pesticides at a large scale to get more production. Though the farmer of Punjab uses the machines, even then the contribution of labourers is too much. This we can estimate from the number of people working in the agricultural sector. In U.S.A. only 3% of population is engaged in agriculture whereas in Punjab 58% people are working in the agriculture sector,
The farmer of Punjab (except a few big farmers) does not practice agriculture like a businessmen. He sows a number of crops in his fields. Two-2 crops are taken at the same time,
The agriculture of Punjab is an intensive type of agriculture. Therefore, the yield per acre is more than that of the U.S.A.

IV. Map Skill

Question 1.
Show two place’s each of following crops on outline map of India. Tea, Wheat, Rice, Cotton, Jute.
Answer:

V. Activity

Question 1.
Name three each of Kharif and Rabi crops mentioning geographical conditions need for each.
Answer:

Crop	Temp	Rainfall	Soils
1. Wheat	10°-20°C	50-100 cm	Clay soil
2. Rice	20°-30°C	100-200 cm	Alluvial soil
3. Maize	18°-27°C	50-100 cm	Levelled plain
4. Cotton	20°-30°	50-100 cm	Simple slope
5. Tea	20°-30°C	150-300 cm	Sloping
6. Jute	29°-35°C	120-150 cm	Alluvial soil

PSEB 8th Class Social Science Guide Our Agriculture Important Questions and Answers

Multiple Choice Questions :

Question 1.
Commercial rearing of silkworm is called
(a) Commercial farming
(b) Pisciculture
(c) Sericulture
(d) Viticulture.
Answer:
(c) Sericulture.

Question 2.
Farming in which the produce is consumed by the farmer’s household is called :
(a) Subsistence
(b) Extensive
(c) Intensive
(d) None of the above.
Answer:
(a) Subsistence.

Question 3.
What does golden filament means?
(a) Cotton
(b) Jute
(c) Silk
(d) Wool.
Answer:
(b) Jute.

Question 4.
Which country is the largest producer of rice in the world?
(a) India
(b) Brazil
(c) China
(d) U.S.A.
Answer:
(c) China.

Question 5.
India is largest producer of _________
(a) Tea
(b) Coffee
(c) Rice
(d) Cotton.
Answer:
(a) Tea.

Question 6.
For what purpose the following machine is used?

(а) For drilling
(b) For showing wheat / rice
(c) For harvesting
(d) For growing vegetables.
Answer:
(c) For harvesting.

Question 7.
In the following picture a plant is shown, name the areas in which plant is found.

(а) Tropical
(b) Temperate
(c) Tropical & temperate
(d) None of these.
Answer:
(c) Tropical & Temperate.

Question 8.
What is the name of farming of fruit shown in this picture?

(а) Horticulture
(b) Sericulture
(c) Pisciculture
(d) Viticulture.
Answer:
(d) Viticulture.

Question 9.
Which of the following crops does this picture resemble?

(a) Paddy (Rice)
(b) Wheat
(c) Maize
(d) Cotton.
Answer:
(a) Paddy (Rice).

Question 10.
What type of crops can be grown on the part of land with plenty of black soil?
(a) Sugarcane
(b) Wheat
(c) Cotton
(d) Jute.
Answer:
(c) Cotton.

Fill in the Blanks :

Question 1.
_________ agriculture is done with machines in sparsely populated areas.
Answer:
Extensive

Question 2.
_________ is called cultivation of grapes.
Answer:
Viticulture

Question 3.
Shifting cultivation is also called _________
Answer:
Slash and burn

Question 4.
Coarse grain are also called _________
Answer:
Millets

Question 5.
Agricultural activity in India is a _________
Answer:
primary activity.

True/False :

Question 1.
Production of fruit and flower is called viticulture.
Answer:
False

Question 2.
Punjab state is the largest producer of wheat.
Answer:
False

Question 3.
Arabica is a variety of coffee.
Answer:
True

Question 4.
Flax is a fibre crop.
Answer:
True

Question 5.
Russia is a leading producer of coffee.
Answer:
False.

Very Short Answer Type Questions

Question 1.
What is meant by agriculture?
Answer:
The word ‘agriculture’ is derived from the Latin words ‘ager’ or ‘agri’ and ’culture’. Ager means soil and culture means cultivation or tilling the soil. Agriculture, thus, means cultivation of soil. But in broader sense, agriculture is growing crops and rearing of livestock. Livestock include animals (cattle, sheep and goat) and birds that are reared for human use.

Question 2.
What are the different forms of the word ‘culture’?
Answer:
The word cuture has many variants like :

Agriculture. Science and art of cultivation on soil, raising crops or livestock.
Sericulture. Commercial rearing of silkworms.
Pisciculture. Breeding of fish for commercial gains.
Viticulture. Cultivation of grapes.
Horticulture. Growing of vegetables, fruits or flowers for commercial use.

Question 3.
What is Sedentary Agriculture?
Answer:
When a farmer practises settled agriculture at a fixed place, it is called sedentary agriculture. Crops can be grown every year at the same field. Organic fertilizers and chemical fertilizers are used to increase the fertility of the soil.

Question 4.
What is mixed farming?
Answer:
In mixed farming, foodgrains, fruit, vegetables are grown along with cattle farming. Fisheries and. bee-hiving is also done. It increases the income of farmers.

Question 5.
What is the main characteristic of plantation farming?
Answer:
Crops are grown on large farms. Tea, coffee, rubber are plantation crops which give yield for many years.

Question 6.
Enlist the fibre crops and the beverage crops.
Answer:
Fibre Crops. Cotton, jute, flax.
Beverage Crops. Tea, coffee, cocoa.

Question 7.
Why the people of rich countries prefer wheat to rice?
Answer:
Wheat contains protein, carbohydrate and vitamins. Therefore, wheat is preferred to rice.

Question 8.
State the conditions of growth, temperature, rainfall and land required for maize.
Answer:

Temperature: 18°C – 27°C, Frost free season.
Rainfall: 50 cm to 100 cm.
Land: Level or rolling.

Question 9.
What are oilseeds? What is their importance?
Answer:
The seeds which provide oil are called oilseeds. These include til, sunflower, rapeseed, etc. These provide us food and meet our daily needs.

Question 10.
Which sources provide fibre? For which purpose fibre from sheep is used?
Answer:
Fiber is obtained from plants and animals. Wool from sheep is used for woollen clothes.

Question 11.
What is the use of cotton fibre?
Answer:
Cotton fibre is used as a raw material for textile industry. It makes fight and strong clothes.

Question 12.
Explain the term ‘farm system’.
Answer:
Agriculture or farming or cultivation is s system called farm system.

Inputs. Include seeds, fertilisers, water, machinery, and labour.
Operations. Ploughing, sowing, irrigation, weeding, and harvesting.
Outputs. Crops, wool, dairy, products, poultry, etc.

Question 13.
Name the main states producing cotton. Account for large production in these states.
Answer:
Maharashtra, Gujarat and Andhra Pradesh produce more than 60% cotton of India. The large production is due to fertile black soils in these states.

Question 14.
Why is tea grown on hill slopes?
Answer:
Tea needs uniform supply of water throughout the year. Water should not stagnate in the roots of tea bush. Hill slopes are well-drained.

Question 15.
How is coffee powder prepared? Which element of it produces excitement in our bodies?
Answer:
Coffee seeds are dried, roasted and grinded to make powder. It contains Caffeine which produces excitement in our bodies.

Question 16.
How is coffee plant grown?
Answer:
Coffee plant is grown in nurseries. After six months, it is transplanted in fields. It starts giving fruit after 3-4 years.

Question 17.
Agricultural development is uneven in different parts. Give one example.
Answer:
Many parts of Africa are not agriculturally developed. But in U.S.A., agriculture is a commercial and profitable occupation.

Question 18.
What is Green Revolution?
Answer:
The increase in agricultural production by introducing scientific methods like; new varieties of seeds, use of fertilizers and good water supply is called green revolution. The increase was in the yields of certain crops like wheat and rice.

Question 19.
Which activities are included in Agriculture?
Answer:
Dairy farming, poultry, honey bee keeping, pisciculture, gur making, flour milks, floriculture all occupations are a part of agriculture.

Question 20.
State two characteristics of Extensive farming.
Answer:

Size of farms is very large.
Yield per acre is less and machines are used for agriculture.

Question 21.
What is the position of Punjab in production of rice?
Answer:
Per hectare yield of rice in Punjab is the highest in India. Punjab produces about 12.2 per cent of total rice of the country. Punjab ranks second in rice production.

Question 22.
If a person has cultivated crops like Tea, Coffee and Cocoa, then identify the types of these crops.
Answer:
Beverage crops.

Short Answer Type Questions

Question 1.
Discuss the main characteristics of shifting cultivation.
Answer:
Shifting Agriculture. In this type of agriculture, first of all, a piece of forest land is cleared by felling trees and burning of trunks and branches. After the land is cleared, crops are grown for two to three years and then the land is abandoned as the fertility of the soil decreases. The farmers then move to new areas and the process is repeated. Dry paddy maize, millets and vegetables are the crops commonly grown in this type of farming. The per hectare yield is low.

Question 2.
Distinguish between dry land farming and wetland farming.
Answer:
Dry land farming. It is practised in areas where the rainfall is low and irrigation facilities are inadequate. Here, emphasis is laid on the conservation of moisture and on crops like jowar, bajra and pulses, which need less water. In dry farming, only one crop is grown in the kharif season.

Wet land farming. It is practised in the areas where rainfall is more than 200 cm per year. It is mostly practised in S.E. Asia. In India, it is practised in West Bengal, Orissa and coastal areas. The main crop is Rice, Sugarcane. Multiple Cropping is done in different seasons.

Question 3.
Distinguish between Individual and Cooperative farming.
Answer:
Individual farming. In this farming, the farmer is the owner of the land. The use of tools, fertilizers and management is in the hands of the farmer. The total income is the personal income of the farmer.

Co-operative farming. In this, the Govt, is the owner of the land. A part of the income goes to the government as tax. The rest of income is divided among the labourers and farmers. This type of agriculture was practised in U.S.S.R.

Question 4.
Write a note on Collective farming.
Answer:
In this type, the farmers join together to form a collective organisation. All the farmers cultivate their own land. The accounts of production is in the hands of the organisation. The decisions are taken for the benefit of farmers. All the profit is distributed among farmers in the ratio of their lands. In India, this type of farming is encouraged by the government.

Question 5.
Describe the favourable conditions for growth of Rice.
Answer:

Temperature: 20°C to 30°C.
Rainfall: 100-200 cm (Irrigation in dry areas)
Soils: Alluvial, clay, loamy and delta or black soils.
Land: Level land suitable for irrigation.
Labour: Cheap and skilled labour.

Question 6.
Describe the cultivation of maize in India and world.
Answer:
Maize: Maize is known as Makka in India, corn in the United States of America, India and Europe. It originated from the American continent. It was introduced in Europe by Columbus and other explorers. It was Native Americans who taught colonizers how to grow maize.

Maize is used as foodgrains and as fodder. It is grown mainly in Russia, Canada and parts of South America. The United States of America is the largest producer. China is the second-largest producer followed by Brazil, Mexico, Argentina and India.

India: Most of Maize is grown in Madhya Pradesh, Andhra Pradesh, Karnataka and Rajasthan. U.P, Himachal Pradesh, J & K, Maharashtra, Punjab and Gujarat are also the producers of Maize. In Punjab, Rupnagar, Amritsar, Hoshiarpur, Jalandhar produce maize.

Question 7.
Write a note on the agricultural development of Punjab.
Answer:
Punjab is one of the leading states of India in agriculture. This is due to :

58% people are engaged in agriculture. 35% of income comes from agriculture.
Soils are fertile. Fertilizers are used.
Mulitple cropping is done. Better seeds are used. Tractors and Harvesters are used.
Irrigation is the basis of agriculture.
Pesticides are used to protect crops.
Machines are used on large farms.

Question 8.
Why agriculture is called the main stay of the Indian Economy?
Answer:
Indian’s main occupation is agriculture. Two-thirds of India’s population is engaged in agriculture. Agriculture is the main stay of the Indian Economy. Agriculture provides food to the teeming millions in India. It sustains 2/3 of our population. It provides raw material to agro-based industries. Agriculture along with forests and fisheries form 45% of our total national income. Our industrial structure is being built on the broad foundation of Indian agriculture. It is also a great earner of foreign exchange.

Question 9.
What are the main features of Agricultural development in India?
Answer:

India is a vast country. More than 70% of its population is dependent upon agriculture for livelihood.
The major foodgrains produced in India are rice and wheat.
Most of farms are not more than one hectare of land.
India is self-sufficient in the production of foodgrains .
In India, half of the total cultivable land is irrigated.

Question 10.
What has been the impact of mechanisation on agriculture?
Answer:
The earlier farmers used simple tools. Gradually on-driven ploughs were introduced. But, now in modern times the techniques have been changed. Now in developed countries all farm operations have been mechanised. It has reduced the number of people engaged in agricultural work. Many people can now work in industries and services.

Question 11.
What is Agriculture?
Answer:
The word Agriculture is derived from two Latin words ‘agri’ and ‘culture’. ‘Agri’ means’soil and ‘culture’ means cultivation or tilling. Agriculture hence refers to the cultivation of soil for growing crops and rearing of livestocks.

Question 12.
Name the factors influencing agriculture.
Answer:
The factors which influence agriculture are :

Relief
Soil conditions
Temperature
Rainfall.

Question 13.
What is plantation agriculture?
Answer:
It is special type of commercial farming which requires large amount of labour, technical efficiency, very large estates and capital. In this type of agriculture a simple crop of tea, rubber, coffee, sugarcane, cashew, banana or cotton is grown. The produce may be processed on the farm itself or in nearby factories. A well developed transport . network is also required.

Tropical regions of the world are major plantation areas. Rubber in Malayasia, coffee in Brazil, tea in India and Sri Lanka are some examples.

Question 14.
Name the different varieties or crops in India.
Answer:

Cereals
pulses and oilseeds
Fibre crops
Beverage crops
Cash crops

Question 15.
Discuss the different types of fibres.
Answer:
Vegetable fibers are obatained from seeds, barks, leaves and fruit cases.
Animals fibres are produced from insects; such as silkworm and animals such as camels, sheep, goats, yaks, Hamas, rabbits, guanacos, alpacas, vicunas and reindeers.

Mineral fibres such as glass is made from silica sand.
Synthetic fibres are derived from chemical treatment of natural cellulose, which is i made from wood pulp.

Question 16.
What do you know about commercial agriculture?
Answer:
In this type of agriculture the main aim is to produce the crop for sale in the market. It can be intensive or extensive agriculture. The farmers try to keep the cost of production low. The framework is done by machines. This type of agriculture is practised in the prairies of North America, Pampas of South America, Steppes of Russia, Western Europe and in some parts of India.

Question 17.
Write the features of Intensive Subsistence Agriculture.
Answer:
It is a type of subsistence agriculture and its features are :

Intensive subsistence agriculture is done on small plot with simple tools.
Done by farmer and his family as labour.
Produce is used mainly by farmer so food grains are grown.
Rice is the main crop. Other crops are wheat, maize, pulses etc are cultivated.
Done mainly in thickly populated areas of south, southeast and east Asia.

Question 18.
Describe the main characteristics of shifting agriculture.
Answer:

In shifting agriculture, a plot of land is cleared by felling trees and burning them.
The ashes are then mixed with soil which works as a fertilizer.
After the soil loses its fertility, the land is abandoned. Cultivators move to a new plot.
It is practised in areas of heavy rainfall and quick generation of vegetation.
It is mainly done in Amazon basin, Tropical Africa, Southeast Asia and northeast India.
Crops like maize, yam, potatoes, and cassava are grown. This is also known as the ‘slash and burn’ agriculture.

Question 19.
Distinguish between :
(i) Subsistence farming and Commercial farming
Answer:

Subsistence Farming	Commercial Farming
1. The practice of farming in which the crops are grown for home consumption by the farmer.	1. The practice of farming in which crops are grown for sale in the market or trade.
2. It is practised on small farms with simple tools and old technology.	2. It is practised on large farms with modern technology.
3. For example The production of wheat in some parts of country.	3. For example The production of sugarcane in U.P.

(ii) Intensive farming and Extensive farming.
Answer:

Intensive Farming	Extensive Farming
1. Production is increased by using higher inputs and better agricultural techniques.	1. Production is increased by bringing more and more land under cultivation.
2. This is practised in areas which are thickly populated.	2. This is practised in areas which are thinly populated.
3. This is practised in areas where there is less land available.	3. This is done in areas where abundant land is easily available.
4. Livestock farming is little developed due to poor pastures.	4. Livestock farming Supplements agriculture due to availability of grasslands.
5. Farms are small in size.	5. Farms are very large in size.

Fill in the blanks :

Question 1.
Shifting agriculture is also known as _________
Answer:
Slash and burn

Question 2.
_________, soil and climate are vital factors for agricultural activities.
Answer:
Topography

Question 3.
Advertising is an example of _________ activities.
Answer:
Tertiary

Question 4.
Jute is grown intensively in _________ and _________
Answer:
India, Bangladesh

Question 5.
Coarse grains are also called _________
Answer:
Millets.

Long Answer Type Questions

Question 1.
What is the importance of cotton? Explain the conditions of growth and areas of production of cotton and jute in India.
Answer:
Cotton. Cotton has been called ‘the universal fibre’. It is one of the most important fibres of all the fibres. It forms the basis of cotton textile industry. Cotton is the leading fibre crop of India. It is known from the writings of Herodotus that cotton has been in use in India since 3000 B.C.

Geographical Conditions of Growth

Temperature. Cotton needs uniformly high summer temperature between 22°C to 32°C. It requires a warm climate with bright sunshine. Frost is harmful to cotton plants.
Rainfall. Cotton needs light to moderate rainfall between 50 to 100 cm.
Irrigation. In arid treas, irrigation is used. It increases the yield per hectare as in Punjab.
Soils. Cotton grows best on rich, well-drained loamy soils or lava soils.

Types of Cotton:

The long-staple cotton. This cotton has a length of 25 mm and above.
The medium staple cotton. This cotton has a staple length between 18 mm to 25 mm.
The short-staple cotton. This cotton has a fibre length of less than 18 mm.

Area of Cultivation
Southern India produces more cotton than Northern India. Gujarat is the leading
producer of cotton in India with a production of 25% of the total production in the country.
1. Black cotton soil region. This is the chief cotton-growing area of India on the ‘lava soil’ of N.W. Deccan Plateau. Gujarat, Maharashtra, and Madhya Pradesh are the major cotton-producing states.

2. Red soil region. Medium staple cotton is grown in the red soil areas including the states of Tamil Nadu, Karnataka, and Andhra Pradesh. The yield is low.

3. Alluvial soil region. Long-staple cotton is grown on the alluvial soils of Northern Plains. The states of Punjab, Haryana, and Rajasthan are the important producers. Punjab has the highest yield per hectare due to its warm climate, fertile soils, and facilities of irrigation.

World Production. The U.S.A. is the leading producer of cotton in the world. China ranks second. India ranks third. Other main producers are Russia, Mexico, Egypt, Sweden, and Pakistan. Egypt is known for long-staple cotton. In the U.S.A., cotton production is decreasing.

Question 2.
Describe the different types of Farming.
Answer:
1. Shifting Agriculture. This farming method is practised by primitive people living in dense forests. The land is prepared by felling trees and burning the trees. People move from one area to another when the soil loses its fertility.

2. Subsistence Farming. In this method, farmers use primitive tools to cultivate their lands. Farmers in these regions produce agricultural goods, which are just sufficient to satisfy their own needs.

3. Commercial Farming. When farmers use modern tools and equipment such as tractors, threshers, winnowers, etc., and produce crops mainly to sell them in the market, it is called commercial farming.

4. Extensive Farming. This method is practised in countries where the population is sparse and the availability of land is more. Farmers use machines to a great extent, as the size of land holdings is large.

5. Intensive Farming. In this method of farming, the same piece of land is used throughout the year continuously. The soil is also very fertile. Farmers use more labourers, seeds that can yield more, better manures, and ensure a regular water supply.

6. Irrigation Farming. It is the type of farming, which mainly depends on irrigation through canals, wells, and tanks. Farmers cultivate their lands throughout the year.

Some of the important river valleys of the world where this method is followed are, the Ganga valley and the Indus valley in India, the Nile valley in Egypt, the Xi Jiang valley in China, Missouri, and San Joaquin valley in the United States of America.

7. Rainfed Farming. In the regions where the rainfall is not only seasonal but also scanty, farmers use different measures to cultivate their lands and use the scarce amount of rainwater efficiently. This is known as rainfed farming.

8. Mono-crop Farming. When the farmers specialize in the production of a single crop or if the soil and other natural factors allow farmers to cultivate only one crop that farming is known as one-crop or mono-crop farming.

9. Double and Multi-crop Farming. When two or more crops are cultivated in a plot of land, it is known as double or multi-crop farming. In this method, farmers apply scientific methods—use seeds that can give high yield, and apply manures in an appropriate manner.

PSEB 8th Class Social Science Solutions Chapter 1 Resources – Types and Conservation

September 25, 2024September 24, 2024 by sachin

Punjab State Board PSEB 8th Class Social Science Book Solutions Geography Chapter 1 Resources – Types and Conservation Textbook Exercise Questions and Answers.

PSEB Solutions for Class 8 Social Science Geography Chapter 1 Resources – Types and Conservation

SST Guide for Class 8 PSEB Resources – Types and Conservation Textbook Questions and Answers

I. Answer the following questions in 1-15 words :

Question 1.
What do you understand by the term ‘resources’?
Answer:
All the useful elements of the environment which satisfy human needs are called resources. Resources are called ‘Gifts of nature’ such as rocks, minerals, soil, rivers, plants, and animals. These are valuable for mankind. Man’s surroundings provide him with resources.

Question 2.
Which are the Natural Resources and who provides us?
Answer:
Forests, minerals, soil, and solar energy are natural resources. These make our environment or surroundings. These natural surroundings provide rsesources.

Question 3.
List all the types of resources.
Answer:
The three categories of resources are :

Natural Resources
Human Resources
Human Made Resources.

Question 4.
Define ‘soil’.
Answer:
The loose and unconsolidated material which forms the upper layer of the crust is called soil. Soil is formed by the breaking of parent rock.

Question 5.
What do we get from Seas?
Answer:
The big water bodies are called seas. Seas provide us organic minerals and power resources, fish, pearls, diamonds, etc. At some places, petroleum is also obtained from sea.

Question 6.
How can you conserve the resources properly?
Answer:
The proper and planned use of resources help in the conservation of resources. These should not be misused.These should not be wasted or destroyed.

II. Answer the following questions in 50-60 words :

Question 1.
Differentiate between Biotic and Abiotic resources.
Answer:

Biotic Resources	Abiotic Resources
1. These are obtained from living things.	1. These are obtained from non-living things.
2. Plants and animals are its examples.	2. Minerals and rocks are examples.
3. These are found in Biosphere and provide food, energy (coal and petroleum) and raw materials.	3. These are found on lithosphere and provide raw materials for industries.

Land: Land is the basis of human activities. It helps in agriculture, setting up of industries, means of transportation, sports, tourism, etc. Houses are built on land.Question 2.
Write a short note on the importance of Land and Soil Resources.
Answer:
The following is the importance of Land and Soil :

Soil: Man grows crops on soils. It provides food and other raw materials to man. Fertile soils support dense population.

Question 3.
From where do we get the minerals and where they used?
Answer:
Minerals are obtained from the interior of earth from rocks. These are metallic and non-metallic. Metallic minerals include iron, copper, gold, silver, aluminium. Non- metallic minerals include coal, mica, manganese and oil. These are used in industries. Before use, these are smelted to make pure.

Question 4.
Explain the Developed and Potential resources with examples.
Answer:

Potential Resources	Developed Resources
1. These are total quantity of a resource found existing in nature.	1. These are only those resources, which have been judged good for use.
2. These have not been put to use.	2. They are put to use fully for economic gain.
3. These are found everywhere.	3. These are not found everywhere.
4. Africa has 40% potential water power resources of world due to large rivers.	4. Africa has only 1% of developed water power resources of world due to lack of technology.

Question 5.
Why should we use the exhaustible resources wisely and with hesitation?
Answer:
The modern civilisation depends upon products—natural as well as man made. With the help of technology, resources are being utilised on a large scale. The exhaustible resources will not last long. 80% of the fossil fuels will be finished in one century With the exhaustion of resources, the civilisation will come to an end. Therefore conservation of resources is necessary. A balance should be maintained between population growth and utilisation of resources so that the continuity of modern civilisation goes on. The natural resources are common heritage. We have to share these with future generations.

Question 6.
What is the contribution of human resources to the development of other resources ?
Answer:
Resources are the elements of Bio-physical environment. But these become resources only when humans preserve these. Coal was always there, but it became a resource only when man used it as a source of energy. So it has been rightly said that the resources are not, they become so. Man uses technology and skill to develop resources. Machines and tools are used. Japan is a very good example where in spite of non existence of resources, the country has progressed to a great extent.

III. Answer the following questions in about 125-130 words :

Question 1.
What do you understand by the resources ? Name their types and explain their importance and methods of conservation.
Answer:
Type of Resources: Resources are generally classified into three types :

natural
human and
human-made.

Natural or man-made resources are of various types. On the bases of life, existence, availability, level of development and utilization these resources can be divided into the following types :

Biotic and Abiotic Resources
Developed and Potential Resources
Exhaustible and Inexhaustible Resources
Soil and Land Resources
Marine-and Mineral Resources
Human Resources

Resource Types

1. Biotic and Abiotic Resources. Biotic resources are those basic resources which originate from the living things. Approximately 85% of the world’s total food depend upon these biotic resources. Plants and other living creatures are included in these types of resources. These resources provide raw material for our industries. Coal and petroleum are also included in the category of biotic resources as they are produced from the plants and animals.
The non-living products like minerals, water etc., which are provided by the nature are called ‘Abiotic Resources’. The minerals are the base of our industry. If we do not use the minerals with care, these will exhaust very soon.

2. Developed and Potential Resources. The resources which are used for some economic gain are termed as ‘Developed resources’. On the other hand, the resources which are available but are not being used or can be used in the future are called ‘Potential Resources’. The rivers descending the mountains can be used to produce electricity and are included in the category of potential resources. When the water of these rivers is used to produce electricity then this water is known as a developed resources. The coal lying underneath the earth is a potential resource whereas the coal which is being used is considered as a developed resource.

3. Exhaustible and Inexhaustible Resources. The resources which are being depleted very fast .because of their continuous and excess use are called exhaustible resources, as petroleum products are being used very fast. The time is not very far away when there will be shortage or non-existence of these resources. Therefore, the exhaustible resources should be used wisely and carefully. ‘

The resources which get renewed as we use them are called inexhaustible resources. For example : We are using sun energy, wind energy, water and forests but these resources do not get depleted rather get renewed. These types resources are being made available continuously. ‘

4. Soil and Land Resources. Soil is a small and uppermost layer of the earth which is formed by breaking of parent rock, due to climate effect and decomposition of plants and animals. Soil is a very important resource for man. It plays an important role in the growth of plants and crops. The soils are of different types like sandy soil, clayey soil, loamy soil, alluvial soil, mountain soil, red soil, black soil etc. Man gives preference to fertile soil for growing crops. The areas with fertile soil are densely populated and are full of economic activities.
Land means the earth’s surface where man carries on his economic or other activities. Man had been using the land resource for a very long time. The land resource is being used for the purpose of agriculture, industry, to develop means of transport, sports, tourism etc. Man uses the land, keeping in view its relief, slope, type of soil, drainage or his requirements.

5. Marine and Mineral Resources Marine Resources. Water is a basic and a very important resource for man. Approximately 71% part of the earth is water. Big water bodies are called ‘seas’. These water bodies provide many biotic, mineral and energy resources. It is believed that the life on the earth started from the seas and oceans. 75% of the total land creatures originated from the water bodies. We get fish, pearls, shells, diamonds etc. from the seas in large quantities. At some places we get petroleum substances from the sea coasts. The fish provide food to the large part of the World’s population.

Mineral Resources: Mineral resources are the substances which are taken from the earth. Basically these are of two types-Metallic and non-metallic minerals. Metallic minerals include iron, copper, silver, gold, aluminium etc.

Petroleum, coal, mica, manganese etc. are some of the non-metallic minerals. The minerals are taken from different types of rocks. The minerals are the bases for our industries, therefore, much significance is attached to them.

6. Human Resources: Man has been awarded the best status of all the creatures produced by the nature. With his intelligence and ability to work, man himself is a very huge resource. Man’s capability plays an important role in the use of all other resources. The development of human resources is reflected from the development of any area. Japan is a very good example where inspite of the deficiency or non-existence of resources, the country has progressed to a great extent. The development of all other resources is incomplete till the human resource is fully developed. Man’s qualities, capacity, educational and technical qualification etc. play an important role in the development.

IV. Activity

Question 1.
Make a list of Hydroelectricity producing dams related to Punjab. Note down the names of rivers on which these dams are situated and names of districts in which these dams have been constructed.
Answer:

Dams	Rivers	Districts
1. Bhakra	Sutlej	Himachal Pradesh
2. Ganguwal	Nangal Hydel Channel	Ropar
3. Kotla	Nangal Hydel Channel	Ropar
4. Pong Dam	Beas	Hoshiarpur
5. Thein Daam	Ravi	Gurdaspur
6. Mukerian	Beas	Hoshiarpur

PSEB 8th Class Social Science Guide Resources – Types and Conservation Important Questions and Answers

I. Multiple Choice Questions :

Question 1.
Which are the biotic resources?
(a) rocks
(b) minerals
(c) plants
(d) hills
Answer:
(c) plants.

Question 2.
What are the basis of classifying resources?
(a) life
(b) achievement
(c) use
(d) all of the above.
Answer:
(d) all of the above.

Question 3.
Which is not termed of human resource?
(a) knowledge
(b) efficiency
(c) intelligence
(d) transparency.
Answer:
(d) transparency.

Question 4.
Which of the following are the ubiquitous resource?
(a) air, water
(b) coal, copper
(c) iron, ore
(d) uranium.
Answer:
(a) air, water.

Question 5.
Nager coil is famous for __________
(a) coal mining
(b) windmills
(c) solar energy
(d) oil refinery.
Answer:
(b) windmills.

Question 6.
In this picture some resources are shown these resources are :

(a) Abiotic resources
(b) Biotic resources
(c) Ubiquitous resources
(d) Human resources.
Answer:
(b) Biotic resources.

Question 7.
We enjoy a lot the beauty of waterfalls mountains, sea etc. Thus, they are natural resources which have ______value.
(a) Ethical Value
(b) Artistic Value
(c) Aesthetic Value
(d) Economic Value.
Answer:
(c) Aesthetic Value.

Question 8.
The following picture shows a specific type of plant. Identify the name of this plant :

(a) Thermal Plant
(b) Nuclear Plant
(c) Biogas Plant
(d) Hydro electric plant
Answer:
(c) Biogas Plant.

Fill in the Blanks :

Question 1.
_______ resources are derived from living things.
Answer:
Biotic

Question 2.
Localised resources are found only in _______ place.
Answer:
certain

Question 3.
The example of human resource is _______
Answer:
people

Question 4.
Anything that satisfy human needs is called _______
Answer:
resource

Question 5.
Non living resources are called _______ resources.
Answer:
Abiotic.

True/False :

Question 1.
Solar and wind energy is an example of renewable resources.
Answer:
True

Question 2.
Environment means set of surroundings.
Answer:
True

Question 3.
Resources are generally classified into two types.
Answer:
False.

Question 4.
Land use depend upon relief, slope, soil etc.
Answer:
True

Question 5.
Coal and petroleum are not biotic resource.
Answer:
False.

Very Short Answer Type Questions

Question 1.
How does something become a resource?
Answer:
That thing which has a value and utility become a resource.

Question 2.
Why is modern man dependent on resources?
Answer:
In early times, human needs were limited. But now-a-days the needs have increased. So man has to depend upon many resources.

Question 3.
Explain, with examples, that the proper use of resources is real development of resources.
Answer:
Before the invention of coal, petroleum, and aeroplane, man was not aware of the Aluminium. Due to utility of Aluminium, its use increased. So we can say that proper use has led to the development of resources.

Question 4.
What are the four basis of classifying resources?
Answer:

life
achievement
stage of development
use.

Question 5.
Which resources are most important to obtain food-resources?
Answer:
To get food resources, agriculture is the most important source as it provides 85% of food resources.

Question 6.
Why coal and petroleum are biotic resources?
Answer:
Coal and petroleum are formed by organic and living plants and animals. So these are grouped as biotic resources.

Question 7.
How can you assess a country as a rich country?
Answer:
The wealth of a country is measured by its resources. The more developed resources make a country richer.

Question 8.
Why are fertile soil areas densely populated with large economic activities?
Answer:
Fertile soils help in growing crops. In fertile soils agriculture is developed. It leads to dense population and many economic activities.

Question 9.
On what factors does the landuse depend?
Answer:
Landuse depends upon relief, slope, soils, drainage and human needs.

Question 10.
What is human resource?
Answer:
Man made resources include machinery, transportation, industries. Human intelligence, knowledge and efficiency is termed as human resource.

Question 11.
Concept of Resource is changing. Why?
Answer:
The concept of resource is changing. It may expand or contract with the development of knowledge and technology.

Question 12.
Name the important types of soil.
Answer:
Sandy soil, Clayey soil, Loamy soil, Alluvial soil, Red soil, Black soil.

Question 13.
Classify resources on the basis of their source of origin.
Answer:
Based on their origin, resources can be biotic or abiotic. For example plants, animals, rocks, minerals, soils etc.

Question 14.
How can we conserve the resources?
Answer:
We can conserve resources by reducing consumption, recycling and reusing things.

Question 15.
What is technology?
Answer:
Technology is human made resource. It is the application of latest knowledge and skill in doing or making things.

Question 16.
The population of India is lesser than only one country. Name that country.
Answer:
China.

Short Answer Type Questions

Question 1.
What is a resource?
Answer:
All the useful elements of environment which satisfy the human needs are called resources. Resources are called ‘Gifts of nature’ such as soils, rivers, plants, animals, rocks and minerals. These are valuable for mankind.

Question 2.
Why are humans also called a resource?
Answer:
They are called a resource because by developing the human skills only the resources can be developed. Resources are not, but they become due to man.

Question 3.
What do you understand by the statement “natural resources have utility and value”?
Answer:
Natural resources have utility and value is true. All the materials that are available in nature have some use or value and that’s what makes them valuable.

Water, air vegetation all have utility or usability, they may or may not have economic value.
Metals have economic value but a landscape may not have; but both are important to satisfy human need.
Time and technology makes them a resource.

Question 4.
What leads to creation of new resources?
Answer:
The knowledge, ideas, inventions and discoveries by people leads to creation of more resources. The discovery of fire led to idea of cooking and other related processes. Invention of wheels led to changes in modes of transport.

Question 5.
Discuss the role of technology in the utilisation of resources.
Answer:
Technology helps to develop the means of production. It increases the value of natural resources. Technology depends upon the human skill and technical knowledge. Mechanism helps in the better utilisation of natural resources. A resource is no resource until it is used.

Question 6.
Distinguish between Natural Resources and Human-made Resources.
Answer:

Natural Resources	Human made Resources
1. They are free gifts of nature.	1. They are not free gifts of nature.
2. They are both renewable and non-renewable.	2. They are non-renewable.
3. They help in the economic development of the country.	3. They help in economic and social development.

Question 7.
Distinguish between Exhaustible and Inexhaustible Resources.
Answer:

Exhaustible Resources	Inexhaustible Resources
1. These resources get exhausted after use.	1. These resources do not get exhausted after use.
2. These resources are regenerated after a very long time.	2. These are renewable or flow resources.
3. Minerals and metals are exhaustible resources.	3. Forests, water power are inexhaustible resources.

Question 8.
What do we mean by a reserve?
Answer:
It refers to that portion of resource which<can be developed profitably with the help of available technology.
For example : High quality iron is used for steel making. But sometimes a low grade iron ore or coal (lignite—Less than 40% carbon content) is used for steel making. Lignite coal in Neyvelli (Tamilnadu) is an example of a reserve resource.

Question 9.
What is meant by human-made resources?
Answer:
They are those resources which are created by human being with the help of machines. Some of the examples are buildings, tools etc.

Question 10.
Give two examples of human made resources.
Answer:
The human made resources are those resources which are created by human beings.

Some examples are :

Buildings,
Machines.

Question 11.
Give an account of natural resources.
Answer:
Natural Resources:
Resouces drawn from (nature) and used without much modification are called natural resources.

Water, soils, minerals are all natural resources.
Many of the resources are free gift of nature.
They can be used directly.
In some cases tools and technology are needed to use a natural resource in the best way.

Question 12.
How are natural resources classified?
Answer:
Natural resources are classified into different groups :

Level of development and use
origin
stock
distribution.

Question 13.
Why natural resources are important?
Answer:

These are important for the economic development of a region or a country.
They are the main sources of our agricultural activities.
They provide raw materials for the industry.
All activities depend on them directly or indirectly.
They help in maintaining the ecological balance of nature. Thus they should be used carefully.

Question 14.
What is meant by conservation?
Answer:
It means the use of the natural resources carefully without any wastage. They are important to us, so they should be used wisely so that they are not exhausted and we may have to face their scarcity.

Question 15.
‘Resources are not resources, they become so.’ Explain.
Answer:
Resources are elements of Bio-physical environment. But these become resources only when humans preserve these. Coal was always there, but it became a resource only when man used it as a source of energy. So it has been rightly said that resources are not resources, they become so.

Question 16.
What are the ill effects of overuse of resdUrces? What are the measures to make the earth habitate? ”
Answer:
Ill effects :
Degradation of resources: The rising demand for various resources has caused degradation or depletion of many valuable resources.

Example :

Overuse of soil has caused infertility in many areas.
Similarly widespread deforestation and killing of birds and animals have endangered many plants and animal species.
The quality of air, water and land resources has also been affected badly due to misuse or overuse of resources.

Question 17.
Distinguish between Renewable and Non-renewable resources.
Answer:

Renewable Resources	Non-renewable Resources
1. These have the capacity to regenerate.	1. These cannot regenerate that quickly.
2. These are free gifts of nature.	2. These are not free gifts of nature.
3. These are those resources which can be used again.	3. These cannot be used again.
4. For example air, water, etc.	4. For example coal, natural oil.

Question 18.
Future of our planet is linked with life support system. Discuss.
Answer:
Our earth is the only planet where life has been found till today. Future of our planet and its people, is linked with our ability to maintain and preserve the life support system that nature provides. This makes it our duty to ensure that the natural environment is preserved and properly managed.

Question 19.
What is sustainable development?
Answer:
By sustainable development, we mean that resources are utilised carefully so that besides meeting the present requirement it also takes care of the future generations.

Question 20.
What is our duty regarding resources?
Answer:
It is our duty to ensure that

The diversity of life on the earth is conserved.
All uses of renewable resources are sustainable.
The damage to natural environment system is minimised.

Question 21.
Distinguish between Natural Resources and Human Resources.
Answer:

Natural Resources	Human Resources
1. They are free gifts of nature.	1. They are not free gifts of nature.
2. They are both renewable and non renewable.	2. They are non renewable.
3. They help in the economic development of the country.	3. They help in the economic and social development.

Question 22.
In how many ways man uses his environment?
Answer:
Environment means set of surroundings. It provides many resources to get food, shelter and clothing. Man uses land for crops, houses, factories,- construction of transport network. Man uses minerals for industries. He uses forests for timber, herbs and shrubs. Man gets fish and other benefits from seas and oceans.

Question 23.
How are development and resources interdependent?
Answer:
Development is possible through resources. Resources are the foundations of development. These have economic significance for human beings. Land, water and air are basic requirements for agriculture. We can’t do agriculture without these resources. Minerals are basic requirement for industries. Industries cannot run without minerals. Thus development and resources are inter-dependent.

Question 24.
Distinguish between actual resources and reserve resources.
Answer:
Actual Resources. Actual resources depend upon physical conditions of environment. These are surveyed. Their quantity is determined and are actually used. Their quantity is known.

Reserve resources are a part of actual resources. These can be made useful with technology. A low grade coal-lignite is a reserved resource in some areas.

Question 25.
Give one example each of developed and potential resources.
Answer:
When the water of river is used to produce electricity, it is called a developed resource. The coal underlying the earth is a potential resource.

Fill in the blanks :

Question 1.
_______ resources are derived from living things.
Answer:
Biotic

Question 2.
Localised resources are found only in places.
Answer:
certain

Question 3.
The example of human resource is _______
Answer:
people

Question 4.
Solar and wind energy is an example of _______
Answer:
Renewable resources

Question 5.
Anything that is used to satisfy a need is called a _______
Answers :
resource

Question 6.
Petroleum in _______ is an example of actual resource.
Answer:
West Asia

Question 7.
_______ is the application of latest knowledge and skill is doing or making things.
Answer:
Technology.

Long Answer Type Questions

Question 1.
Write a detailed note on the conservation of resources with special reference to marine and mineral resources.
Answer:
Conservation of Resources. Man depends upon his environment to meet his needs. He uses water, land, soil, vegetation, etc. to satisfy his needs. Man is using these resources at such an alarming rate that there will be a serious shortage of these resources in the near future. Natural resources are of a very limited supply. So conservation of resources is essential for the survival of man.

To some people, conservation means that the available resources should not be used. These should be held back. But conservation of resources means a careful and rational utilization of resources. These resources should be used intelligently for the welfare of mankind. It means careful control and management of resources so that these may be used for the benefit of future generations also. These should be preserved from reckless exploitation and wanton destruction. These resources should not be wasted in a short time. The resources should be maintained in a healthy condition for their use so as to achieve a high standard of living for mankind.

Importance:
Conservation of all resources has an economic, scientific, and aesthetic value for mankind :

Conservation of resources is necessary as these are the basis of the economic activities of man.
Resources must be conserved to meet the different human needs.
Conservation of resources is essential as life depends on these useful elements of the environment such as air, water, soil, rocks, forests, and water bodies.
Many areas of the world are still under-developed because the resources of these areas have not been used in a planned and rational manner.

PSEB 8th Class Science Solutions Chapter 4 Materials: Metals and Non-Metals

September 25, 2024September 24, 2024 by Prasanna

Punjab State Board PSEB 8th Class Science Book Solutions Chapter 4 Materials: Metals and Non-Metals Textbook Exercise Questions and Answers.

PSEB Solutions for Class 8 Science Chapter 4 Materials: Metals and Non-Metals

PSEB 8th Class Science Guide Materials: Metals and Non-Metals Textbook Questions and Answers

Exercises

Question 1.
Which of the following can be beaten into thin sheets?
(a) Zinc
(b) Phosphorus
(c) Sulphur
(d) Oxygen.
Answer:
(a) Zinc.

Question 2.
Which of the following statements is correct?
(а) All metals are ductile.
(b) All non-metals are ductile.
(c) Generally, metals are ductile.
(d) Some non-metals are ductile.
Answer:
(a) All metals are ductile.

Question 3.
Fill in the blanks.
(a) Phosphorus is very ……………… non-metal.
(b) Metals are …………. conductor of heat and ……………… .
(c) Iron is ……………… reactive than copper.
(d) Metals react with acids to produce ……………………. gas.
Answer:
(a) reactive.
(b) good, electricity.
(c) more.
(d) Hydrogen.

Question 4.
Mark ‘T’ if the statement is true and ‘F’ if it is false.
(а) Generally, non-metals react with acids.
(b) Sodium is a very reactive metal.
(c) Copper displaces zinc from zinc sulphate solution.
(d) Coal can be drawn into wires.
Answer:
(a) True
(b) True
(c) False
(d) False

Question 5.
Some properties are listed in the following Table. Distinguish between metals and non-metals on the basis of these properties. (From Board M.Q.P.)

Properties	Metals	Non-metals
1. Appearance
2. Hardness
3. Malleability
4. Ductility
5. Heat Conduction
6. Conduction of electricity

Answer:
Differences between metals and non-metals.

Properties	Metals	Non-metals
1. Appearance	Silvery or grey in colour.	Different coloured non-metals.
2. Hardness	Solid at room temperature.	Solid, liquid or gas at room temperature and brittle.
3. Malleability	Can be beaten into sheets.	Non-malleable.
4. Ductility	Can be drawn into wires.	Non-ductile.
5. Heat Conduction	Present.	Absent.
6. Conduction of electricity	Possible.	Not Possible.

Question 6.
Give reasons for the following :
(a) Aluminium foils are used to wrap food items.
(b) Immersion rods for heating liquids are made up of metallic substances.
(c) Copper cannot displace zinc from its salt solution.
(d) Sodium and potassium are stored in kerosene.
Answer:
(a) Aluminium foils are used to wrap food items because aluminium is malleable and less reactive to air and water.

(b) Immersion rods for heating liquids are made of metallic substances because metals are good conductors of heat and electricity.

(d) Sodium and potassium are very reactive metals. They react with air and water to form respective oxides and hydroxides. So, they are kept in kerosene.

Question 7.
Can you store lemon pickle in aluminium utensil ? Explain.
Answer:
No. Lemon pickle cannot be stored in aluminium utensils because acid present in lemon pickle reacts with aluminium to produce poisonous chemicals, which can cause food poisoning or other health hazards.

Question 8.
Match the substances given in Column A with their uses given in Column B.

Column A	Column B
(i) Gold	(a) Thermometers
(ii) Iron	(b) Electric wire
(iii) Aluminium	(c) Wrapping food
(iv) Carbon	(d) Jewellery
(v) Copper	(e) Machinery
(vi) Mercury	(f) Fuel

Answer:

Column A	Column B
(i) Gold	(d) Jewellery
(ii) Iron	(e) Machinery
(iii) Aluminium	(c) Wrapping food
(iv) Carbon	(f) Fuel
(v) Copper	(b) Electric wire
(vi) Mercury	(a) Thermometers.

Question 9.
What happens when
(a) Sulphuric acid is poured on a copper plate ?
(b) Iron nails are placed in copper sulphate solution ?
Write word equations of the reactions involved. (From Board M.Q.P.)
Answer:
(a) When sulphuric acid is poured on copper plate, Hydrogen gas is given out.
PSEB 8th Class Science Solutions Chapter 4 Materials Metals and Non-Metals 1

(b) When iron nails are placed in copper sulphate solution, iron displaces copper from its salt to form iron sulphate
PSEB 8th Class Science Solutions Chapter 4 Materials Metals and Non-Metals 2

Question 10.
Saloni took a piece of burning charcoal and collected the gas evolved in a test tube.
(а) How will she find the nature of the gas ?
(b) Write down word equations of all the reactions taking place in this process.
Answer:
(a) To test the nature of the gas:
1. Take blue/red litmus solution turnwise into the jar of gas collected. It will turn blue litmus red while red litmus will remain unaffected. This shows that gas is acidic in nature.
2. Add some water to the jar. The liquid for turns blue litmus red showing acidic nature of the gas.

(b) When a charcoal is burnt, it reacts with oxygen to form an acidic oxide called
carbon dioxide.
PSEB 8th Class Science Solutions Chapter 4 Materials Metals and Non-Metals 3

The acidic oxide, carbondioxide, dissolves in water to form an acid called Carbonic acid
PSEB 8th Class Science Solutions Chapter 4 Materials Metals and Non-Metals 4

Question 11.
One day Reeta went to a jeweller’s shop with her mother. Her mother gave an old gold jewellery to the goldsmith to polish. Next day when they brought the jewellery back, they found that there was a slight loss in its weight. Can you suggest a reason for the loss in weight ?
Answer:
Jewellers usually use a chemical solution named aquaregia for cleansing the jewellery. This solution is capable of dissolving gold in it. So, loss in weight is found.

Multiple Choice Questions

Question 1.
In order to keep the flow of electricity continue in circuit, which of the following items should be used in place of iron nail in the given circuit. (From Board M.Q.P.)
PSEB 8th Class Science Solutions Chapter 4 Materials Metals and Non-Metals 5
(a) Graphite
(b) Plastic
(c) Wood
(d) Rubber.
Answer:
(a) Graphite.

Question 2.
Sodium metal is stored ………………….
(a) In water
(b) In kerosene oil
(c) In Air
(d) None of these.
Answer:
(b) In kerosene oil.

Question 3.
When strip of iron is placed in moist air then after some days a layer is deposited over it which has colour:
(a) Green
(b) Red
(c) Dirty
(d) None of these.
Answer:
(b) Red.

Question 4.
Which of the following statements is correct ?
(a) All metals are ductile
(b) All non-metals are ductile.
(c) Generally metals are ductile
(d) Some non-metals are ductile.
Answer:
(c) Generally metals are ductile.

Question 5.
Which of the following is a non-metal ?
(a) Iron
(b) Carbon.
(c) Gold
(d) Calcium.
Answer:
(b) Carbon.

Question 6.
Phosphorus is stored in:
(a) Water
(b) Air
(c) Oil
(d) None of the above.
Answer:
(a) Water

Question 7.
The metal which is found in liquid form is:
(a) Copper
(b) Silver
(c) Mercury
(d) Sodium.
Answer:
(c) Mercury.

Question 8.
Which metal is a good conductor of electricity and heat ?
(a) Sodium
(b) Potassium
(c) Copper
(d) None of the above.
Answer:
(c) Copper.

Question 9.
The best conductor of electricity is:
(a) Copper
(b) Lead
(c) Aluminium
(d) Silver.
Answer:
(d) Silver

Question 10.
Red colour makes the solution of litmus blue because of:
(a) Metal oxide
(b) Sulphur dioxide
(c) Carbondioxide i
(d) None of the above.
Answer:
(a) Metal oxide.

Question 11.
Non-metal on the base of hardness is:
(a) Iron
(b) Aluminium
(c) Copper
(d) Coal.
Answer:
(d) Coal.

Question 12.
Which of the following gas is released when a metal react with acids ?
(a) Oxygen
(b) Hydrogen
(c) Sulphur dioxide
(d) Nitrogen
Answer:
(b) Hydrogen.

Very Short Answer Type Questions

Question 1.
Name the property because of which metals can be beaten into thin layers or sheets.
Answer:
Malleability.

Question 2.
What is ductility ?
Answer:
Ductility. The property by which metals can be drawn into wires, is called ductility.

Question 3.
Name the most ductile metal.
Answer:
Silver.

Question 4.
Name the metal which exists in the liquid state.
Answer:
Mercury.

Question 5.
Name one metal which is poor conductor of electricity.
Answer:
Lead.

Question 6.
Which metal is used in thermometer ?
Answer:
Mercury.

Question 7.
Which metal and non-metal is liquid at ordinary temperature ?
Answer:
Metal – Mercury
Non-Metal – Bromine.

Question 8.
Write two properties of metals.
Answer:
Malleability and Ductility.

Question 9.
Name two metals which are good conductors of both heat and electricity.
Answer:
Copper and Aluminium are good conductors of both heat and electricity.

Question 10.
Name three metals which occur in the native state.
Answer:

Silver
Gold
Platinum occur in the native state.

Question 11.
List two metals which are easy to cut.
Answer:

Sodium
Potassium.

Question 12.
What is that property, which allows metals to be drawn into wires, called ?
Answer:
Ductility.

Question 13.
Which metals are used to make electric wires ?
Answer:
Copper and Aluminium.

Question 14.
Which metal is constituent of haemoglobin ?
Answer:
Iron.

Question 15.
Write a chemical reaction of Iron with Oxygen.
Answer:
PSEB 8th Class Science Solutions Chapter 4 Materials Metals and Non-Metals 6

Question 16.
Write the chemical equation for the reaction of Zn with Oxygen.
Answer:
PSEB 8th Class Science Solutions Chapter 4 Materials Metals and Non-Metals 7

Question 17.
The set of metals in order of their increasing chemical reactivity is given below:
Silver, copper, lead, iron, zinc, magnesium and sodium.
(a) Which of the above metals is stored in kerosene ?
(b) Which metals will react with cold water ?
(c) Which gas will be liberated when metals react with cold water ?
(d) Which of the metals will react with oxygen when heated ?
(e) Which of the metals becomes black in the presence of hydrogen sulphide, H₂S ?
(f) Which of the metals burns with white bright flame in oxygen ?
Answer:
(a) Sodium
(b) Sodium and Magnesium
(c) Hydrogen
(d) Magnesium
(e) Silver
(f) Magnesium.

Question 18.
Name five metals which are used in daily life.
Answer:
Metals used in daily life.

Aluminium
Iron
Copper
Zinc
Tin.

Question 19.
Name five metals which are used in our industrial processes.
Answer:
Metals used in Industrial Processes.

Aluminium
Iron
Copper
Nickel
Zinc.

Question 20.
Why do Sodium, Zinc, Magnesium and Aluminium not occur in their pure state ?
Answer:
Because these react with air, water and acids.

Question 21.
Name atleast two metals which do not react with air, water and acids.
Answer:

Gold
Platinum.

Question 22.
Of what property, are metals used in jewellery ?
Answer:
Metallic lustre.

Question 23.
What is the colour of copper metal ?
Answer:
Eeddish-brown colour.

Question 24.
Of Iron, Copper and Magnesium, which metal can be cut easily ?
Answer:
Magnesium.

Short Answer Type Questions

Question 1.
What is the difference between a metal and a non-metal ? What is the total number of naturally occurring elements ?
Answer:
Metals have metallic lustre, are malleable, ductile, good conductors of heat and electricity, hard and combine with oxygen to form basic oxides.

Non-metals have dull lustre, not malleable and non-ductile, bad conductors of heat and electricity, brittle and combine with oxygen to form acidic oxides. The total number of naturally occurring elements is 92.

Question 2.
Why is Potassium metal not stored in water ?
Answer:
Potassium is a reactive metal. It reacts with air even at room temperature. Also it reacts with water at room temperature and catches fire. Hence, it is not stored in water but kept under kerosene oil.
PSEB 8th Class Science Solutions Chapter 4 Materials Metals and Non-Metals 8

Question 3.
State two physical properties on the basis of which metals may be distinguished from non-metals.
Answer:

Metals are good conductors of heat and electricity. Non-metals are bad conductors of heat and electricity.
Metals have a shiny appearance, that is, they show a metallic lustre. Nonmetals have a dull lusture. They generally do not reflect light well.

Question 4.
State one chemical property which may be used to distinguish a metal from a non-metal.
Answer:
Metals when burn, combine with oxygen to form metallic oxides which are basic in nature, whereas non-metals combine with oxygen to form acidic oxides. This property can be used to distinguish a metal from a non-metal.

Question 5.
Why is sodium stored in kerosene oil ?
Answer:
Sodium is highly reactive metal. It readily combines with oxygen when exposed to air and sometimes it even catches fire. It also reacts with water forming its hydroxide. To prevent its oxidation, sodium is stored under kerosene oil.

Question 6.
Explain the following:
(а) Acidic oxides
(b) Basic oxides.
Answer:
(a) Acidic Oxides. These are the oxides of non-metals and give acids when dissolved in water.
Examples : CO₂, SO₂ etc.

(b) Basic Oxides. These are the oxides of metals and give alkaline or basic solutions in water.
Examples : Sodium oxide, Calcium oxide etc.

Question 7.
Explain the occurrence of metals in nature.
Answer:
Occurrence of Metals in Nature. Metals occur in the nature in free as well as in combined state.
1. Free or Native State. The metals which are not attacked by air and moisture generally occur in the free or native state e.g. metals like gold, platinum etc.

2. Combined State. Metals generally occur in nature in the form of compounds
such as oxides, sulphides etc. These metals are said to occur in the combined state, e.g. Aluminium oxide.

Question 8.
What do you understand by ductility and malleability of a metal ? Give examples of two metals which are both ductile and malleable.
Answer:
Ductility.
It is the property of metals by virtue of which metals can be drawn into thin unbroken wires. Metals exhibiting this property are called ductile.
Examples : Copper, Aluminium, Silver, Gold.

Malleability. It is the property of metals by virtue of which Metals which can be beaten into thin sheets and twisted or bent without breaking. Metals showing this property are called malleable.
Examples : Gold, Silver, Aluminium.
Examples of two metals which are both malleable and ductile :
Aluminium and Gold.

Question 9.
Silver does not combine easily with oxygen but silver jewellery tarnishes after some time. How ?
Answer:
Silver does not combine easily with oxygen of the air. But it readily combines with sulphur compounds such as hydrogen sulphide present in the air to form a black coating of silver sulphide. Therefore, silver jewellery tarnishes after some time.

Question 10.
Why do gold ornaments look new even after several years of use ?
Answer:
Gold does not tarnish. That is, it never corrodes as it is non-reactive. It is unaffected by air, water and acids. This is why gold ornaments look new even after several years of use.

Question 11.
Magnesium and copper metals are heated directly over a flame. Which of these will burn in air ? Which is more reactive ?
Answer:
When magnesium and copper are heated directly over a flame, magnesium will burn in air. Magnesium is more reactive.

Question 12.
CuSO₄ + Fe → FeSO₄ + Cu
FeSO₄ + Zn → ZnSO₄ + Fe
On the basis of the above reactions, indicate which is the most reactive and which is the least reactive metal out of zinc, copper and iron ?
Answer:
In the first reaction, iron displaces copper from copper sulphate solution, therefore, iron is more reactive than copper. In the second reaction zinc displaces iron from iron sulphate, therefore, zinc is more reactive than iron. Therefore, zinc is the most reactive metal while copper is the least reactive.

Question 13.
Why are pickles, chutney and citrus fruits not stored in iron and aluminium utensils ?
Answer:
Certain foodstuffs, particularly citrus fruits, chutney, pickles and curd, which contain acids tend to attack kitchen utensils made of aluminium and iron forming poisonous salts. Iron and aluminium utensils are, therefore, not used to store pickles, chutney and citrus fruits.

Question 14.
What would you observe when a strip of zinc is dipped in the solution of copper sulphate ?
Answer:
Zinc being more reactive would replace copper from its salt solution i.e. copper sulphate.
Zn + CuSO₄ → ZnSO₄ + Cu

Question 15.
Can copper displace iron from iron sulphate solution ? Give reasons.
Answer:
No, because copper is less reactive than iron. As a result, it can’t replace iron from its salt solution i.e. iron sulphate. Only more reactive metals can replace less reactive metals from their salt solutions. Vice-versa is not possible i.e., less reactive metals cannot replace more reactive metals from their salt solutions.

Question 16.
Why does aluminium vassel lose its lusture after sometime ?
Answer:
Aluminium is a reactive metal. During its use, it comes in contact with air and water when it forms dull coating of aluminium oxide on its surface. Hence the vessel loses its shine.

Question 17.
Why aluminium metal is preferred to copper for making cooking utensils ? Give two reasons.
Answer:
Because of the following two reasons, aluminium is preferred to copper for making cooking utensils.

It is very light and is a good conductor of heat.
It is not readily attacked by acids present in the food materials to be cooked.

Question 18.
What is corrosion ? What are the different ways to reduce corrosion ?
Answer:
Corrosion. Metals when exposed to moist air get covered with dull layer.
This layer can be easily removed giving place to the next such layer to be formed. In this way, metal is eaten up or corroded and the process is called corrosion.
Ways to reduce corrosion:

By covering the metal with paint
By applying oil or grease on the surface of metal.
By coating the metal with some other metal which is not easily corroded by passing electricity.
By making an alloy.

Question 19.
Sodium occurs in the combined state where as Gold in its native state, why ?
Answer:
Sodium is the most reactive metal. It readily combines with air and water to form its compounds. So it occurs as compound. On the other hand Gold is the noble metal and is not attacked by air, water or acids so it exists in its native form.

Question 20.
Does copper rust ? What will happen if copper is exposed to moist air ?
Answer:
Copper does not rust. When copper is exposed to moist air for long, it acquires a dull green coating. The green material so formed is a mixture of Copper hydroxide [CU(OH)₂] and Copper carbonate [CuCO₃], The following reaction takes place:
PSEB 8th Class Science Solutions Chapter 4 Materials Metals and Non-Metals 9

Question 21.
Give reasons for the following:
(i) Aluminium is used in making parts of aeroplane.
(ii) Copper is used in making electric wires.
(iii) Silver is used in making mirrors.
(iv) Graphite is used as an electrode in the Dry cell.
(v) Iron is used in constructing bridges and dams.
Answer:
(i) Aluminium being light and strong metal is used in making parts of aeroplanes.
(ii) Copper is a good conductor of electricity. So, it is used for making electric wires.
(iii) Silver is very shining white metal and has, therefore, high reflecting power.
(iv) Graphite is a good conductor, so it used for making electrode in dry cells.
(v) Iron being strong and rigid metal is used in the construction of bridges and dams.

Long Answer Type Questions

Question 1.
Give general physical properties of metals.
Answer:
General physical properties of metals:

Metals have a shiny appearance, i.e. they show metallic lustre.
Metals are generally hard and their hardness varies from metal to metal.
Most metals are malleable, i.e. they can be hammered into thin sheets.
Metals are ductile and, therefore, can be drawn into wires.
Metals are good conductors of heat and electricity. Electricity flows most readily through gold, silver, copper and aluminium.
Metals are generally sonorous i.e. metals make sound when hit with an object.
All metals except mercury exist in solid form at room temperature.
Metals have high melting points.

Question 2.
Give general physical properties of non-metals.
Answer:
General physical properties of non-metals:

Lustre. Non-metals possess dull lustre, i.e., they do not reflect light well. Exceptions are graphite and diamond.
Conductivity. Non-metals are poor conductors of heat and electricity. Exception is graphite.
State. Non-metals may occur as solids or liquids or gases at room temperature. For example Sulphur, Carbon and Iodine are solids. Bromine is a liquid. Chlorine and nitrogen are gases.
Malleability. Non-metals are not malleable but they are brittle. Non-metals break into small pieces when hammered.
Hardness. Non-metals are generally not hard but diamond is exception. Diamond is the hardest known substance.
Ductility. Non-metals cannot be drawn into wires and are, therefore, not ductile
Melting and Boiling Point. Non-metals have low melting and boiling points. A majority of non-metals are gases. Exception is graphite which has a high melting point.

Question 3.
How do metals react with acids ?
Answer:
Reaction of metals with acids :
1. Active metals like zinc, magnesium, iron etc. which lie above hydrogen in the electrochemical series or activity series can displace hydrogen from dilute mineral acids such as hydrochloric acid and sulphuric acid.
PSEB 8th Class Science Solutions Chapter 4 Materials Metals and Non-Metals 10

2. The metals which lie below hydrogen don’t displace hydrogen from dilute mineral acids such as hydrochloric acid, sulphuric acid etc.
For example, copper does not react with dil. HCl.

Question 4.
How do metals react with water ?
Answer:
Reaction of metals with water. Different metals have different reactivities with water. All metals react with water under different conditions to produce hydrogen gas.
1. Active metals like Na, K react with water at room temperature.
PSEB 8th Class Science Solutions Chapter 4 Materials Metals and Non-Metals 11
The reaction is so violent and exothermic that the evolved hydrogen catches fire.

2. Less active metals like Mg, Zn, Al, react with boiling water.
PSEB 8th Class Science Solutions Chapter 4 Materials Metals and Non-Metals 12
3. Metals like Fe, Ni react very mildly with steam

Question 5.
Which of the following displacement reaction cannot occur ?
(a) CUSO_4(aq) + Fe → FeSO_4(aq) + Cu
(b) FeSO_4(aq) + Zn → ZnSO_4(aq) + Fe
(c) ZnSO_4(aq) + Pb → PbSO_4(aq) + Zn
(d) 2AgNO_3(aq) + Cu → Cu(NO₃)₂ + 2Ag
(e) MgSO_4(aq) + Cu → CuSO₄ + Mg
Answer:
A more reactive metal (placed higher in the activity series) can displace the less reactive metal from its solution. Out of the above five reactions.
(c) cannot occur because zinc is more reactive than lead.
(e) cannot occur because magnesuim is more reactive than copper.

Question 6.
Name three metals that you come across in your daily life and also give their uses.
Answer:
We come across directly or indirectly the following metals in our daily life:

Iron
Copper
Aluminium

1. Uses of Iron :

Iron mixed with other metals is largely used in making trains, automobiles and other machine parts.
Iron mixed with cement is used in constructing big buildings and dams.
Iron is used in making bridges and boilers for industry.

2. Uses of Copper:

It is used for making cooking utensils,
It is used in making photoframes, coins and statues.
It is used for making electrical wires.

3. Uses of Aluminium:

It is used for making aeroplanes
It is used for making electric wires and parts of electric gadgets.
Aluminium foils are used as packing material.

Question 7.
Distinguish between metals and non-metals on the basis of their chemical properties.
Answer:
Distinction between Metals and Non-metals

Property	Metals	Non-Metals
Chemical Properties- 1. Nature of Ions	Metals are electr-opositive elements and lose electrons to become electro-positive ions.	Non-metals are electro-negative elements and gain electrons to form negative ions.
2. Nature of Oxides	Form basic oxides	Form acidic oxides.
3. Reaction with Water	Mostly displace hydrogen.	Do not react with water.
4. Reaction with Acids	Metals above hydrogen in the activity series displace hydrogen from	Non-metals do not react with dilute acids.
5. Nature of Hydrides	Metals react with hydrogen to form ionic hydrides.	Form covalent hydrides.
6. Nature of Chlorides	Metals combine with chlorine to form solid ionic chlorides which conduct electricity.	Non-metals combine with chlorine to form covalent chlorides which do not conduct electricity.

Question 8.
Give general chemical properties of non-metals.
Answer:
1. Reaction with Air or Oxygen. Non-metals react with air or oxygen to form their corresponding oxides which are acidic in nature. These oxides turn blue litmus red.
PSEB 8th Class Science Solutions Chapter 4 Materials Metals and Non-Metals 14

2. Reaction with Hydrogen. Non-metals like carbon, Nitrogen, and Phosphorous react with Hydrogen to form different compounds.
PSEB 8th Class Science Solutions Chapter 4 Materials Metals and Non-Metals 15

3. Reaction with other non-metals. Non-metals react with other non-metals to form compounds
PSEB 8th Class Science Solutions Chapter 4 Materials Metals and Non-Metals 16

4. Reaction with Acids. Non-metals react with acids to form corresponding oxyacids.
PSEB 8th Class Science Solutions Chapter 4 Materials Metals and Non-Metals 17