Important Questions

Punjab State Board PSEB 10th Class Science Important Questions Chapter 7 Control and Coordination Important Questions and Answers.

PSEB 10th Class Science Important Questions Chapter 7 Control and Coordination

Long Answer Type Questions

Question 1.
Draw a well labeled diagram of the human brain and mention the functions of its various parts.
Answer:
Human brain is divided into three parts- Fore brain, mid brain and hind brain.
1. The Fore Brain: It is the largest part of the brain. It consists of the following parts :
(a) Olfactory lobes: They are concerned with sense of smell.
(b) Cerebrum: It is the most important and largest part of the fore brain. It is divided into two halves called the cerebral hemispheres. The two hemispheres are connected by a tract of nerve fibres called corpus callosum.

The functions of cerebrum are :

• It analyses the sensory signals in the association areas and thinking of a proper response.
• It sends response signals (motor signals) to the muscles through the motor areas.
• It stores memory of different experiences and uses this memory to generate proper responses.
• It is the seat of understanding language, memory, knowledge and logical thinking.

Section of human brain

(c) Thalamus: It is situated underneath (below) the cerebrum. Its function is to coordinate the incoming sensory signals to the cerebrum and outgoing motor signals from it.

• It controls many of the body’s important activities and feelings’ such as hunger, thirst, temperature regulation, sleep, emotional behaviour and sexual activity.
• It produces and secretes hormones that control the functioning of the pituitary gland situated just below it. It also controls the function of internal body organs by means of the autonomic nervous system.

2. The Mid Brain: It consists of crura cerebri and optic lobes. It is the topmost structure of the brain stem :

• It has centres relating to pain, temperature and touch.
• It controls many involuntary actions of the body.
• It has a collection of cells that control functioning of eyes and ears.

3. The Hind Brain: It consists of the pons, cerebellum and medulla oblongata :
(a) Pons. It is a bulging structure situated below the mid brain. It consists of large bundles of nerve fibres that interconnect different regions of the brain.

(b) Cerebellum. It is located at the lower back side of the brain under the cerebrum. Its functions are as follows :

• Maintaining the posture and balance of the body by controlling the muscles.
• It also controls the voluntary actions of the body by controlling motor signals coming from the cerebrum.

(c) Medulla oblongata. It is long stalk-like lowermost portion of the brain stem.. At the lower side it is connected with the spinal cord. It controls many involuntary actions such as salivation, vomiting, blood pressure, respiration and heart beat.

Question 2.
Describe the structure of spinal cord.
Answer:
The spinal cord extends from the foramen magnum where it is continuous with the medulla. It is a vital link between the brain and the body, and from the body to the brain. The spinal cord is 40 to 50 cm long and 1 cm to 1.5 cm in diameter. Two consecutive rows of nerve roots emerge on each of its sides. These nerve roots join distally to form 31 pairs of spinal nerves. The spinal cord is a cylindrical structure of nervous tissue composed of white and grey matter, is uniformly organized. The spinal nerve contains motor and sensory nerve fibres to and from all parts of the body.

Spinal Cord

Although the spinal cord constitutes only about 2% of the central nervous system (CNS), its functions are vital.
Knowledge of spinal cord functional anatomy makes it possible to diagnose the nature and location of cord damage and many cord diseases.

Question 3.
What is reflex action? Explain giving an example. What is reflex arc?
Answer:
Reflex action is a quick action in response without involvement of the thought process. It is controlled through the spinal cord in which transfer of impulse takes place from sensory neuron to the motor neuron. The path through which the signal travels during reflex action is called the reflex arc. As the reflex arc is a shorter route reflex action takes place in a fraction of a second. For example, if a person accidentally hits something on the leg, the pain receptors in the skin receive the pain and generate an electric signal. This impulse is sent by the sensory neuron to the spinal cord. In the spinal cord the impulse is transferred quickly to the motor neuron, which relays it to the leg muscles for quick action.

Question 4.
List the components of nervous system. What is a synapse? Explain what are its kinds.
Answer:

• Nervous system: It consists of central nervous system, peripheral nervous system and autonomic nervous system.
• Central nervous system: It consists of brain and spinal cord. It is the main controlling centre of the body.
• Peripheral nervous system: It consists of cranial and spinal nerves.
• Autonomic nervous system consists of a special set of peripheral nerves that innervate organs like heart, lungs, digestive tract.

Autonomic nervous system can be divided into two divisions :
(a) Sympathetic nervous system.
(b) Parasympathetic nervous system.

Synapse: Synapse is the close proximity of the axon of one neuron and the dendrite or cvton of another neuron with a gap. In a synapse, the transmitting cell is called the presynaptic cell, and the receiving cell is termed the postsynaptic cell. A narrow gap, called synaptic cleft, separates the presynaptic cell from the postsynaptic cell. Hence, an action potential occurring in the membrane of the presynaptic cell cannot be directly transmitted to the membrane of the postsynaptic cell.

Question 5.
What are phytohormones? Classify the main groups.
Answer:
Growth regulators: Growth is regulated not only by environmental factors like light and temperature but also by certain chemical substances within the plants. These substances are known as plant hormones, growth hormones, phytohormones or growth regulators. A plant hormone can be defined as a chemical substance, which is capable of translocation and regulating one or more physiological reactions, when present in low concentrations.

• Auxins
• Gibberellins
• Cytokinins
• Ethylene.
• Abscisic acid (ABA).

On the basis of their effect, phytohormones can be divided into two groups :
(а) Growth promoters: These stimulate the plant growth e.g. auxins, gibberellins, cytokinins and ethylene.
(b) Growth inhibitors: These inhibit or retard plant growth e.g. ABA.

Question 6.
Explain the following :
(i) Hydrotropism (ii) Thigmotropism (iii) Chemotropism.
Or
Explain briefly the various types of plant movements.
Answer:
Movements: Movements of plant parts can mostly be classified as growth movements and turgor movements. The growth movements are autonomic. The movements induced by external stimuli are called paratonic. Tropic movements can be of various types depending on the nature of external stimulus e.g. geotropism, thigmotropism, thermotropism, hydrotropism, chemotropism and phototropism.

Nastic movements are in the bifacial organ. Seismonastic movements are observed in Mimosa pudica.

• Phototropism: Movements towards stimulus of light.
• Geotropism: Movements towards stimulus of force of gravity.
• Hydrotropism: The term hydrotropism is applied to growth movements in response to external stimulus of water. Roots, normally or positively hydrotropic (i.e., they bend towards the source of water).
• Thigmotropism: Thigmotropism is the tropic movement in the plants due to the stimulus of touch, tactile, mechanical or rubbing.
• Chemotropism: When chemical substances are the external stimuli, the growth movement is termed as chemotropism. The best example is the growth of pollen tube through stigma and style towards the embryo sac with the stimulus of chemical substances present in the carpel.

Question 7.
Describe various endocrine glands.
Answer:
Endocrine glands and their secretions

Short Answer Type Questions

Question 1.
What are hormones? Why are they called chemical messengers? What are the general properties of hormones?
Answer:
Hormones: They are informational molecules secreted by the endocrine cells in one part of the body in response to changes in external or internal environment, and carried by blood to another part where they stimulate or inhibit specific physiological processes for the good of the body as a whole.

In other words, the hormones are chemical messengers that regulate the biological processes in the organisms as they carry the information in the form of chemicals.

General properties of hormones

• The hormones themselves do not create biochemical processes. They only modify the existing metabolic processes and change the rate of action.
• Hormonal actions are usually long lasting than those produced by nerve impulses.
• They are effective in minute quantities.
• They are secreted in response to specific stimuli.
• They are secreted independent of one another.

Question 2.
What is phototropism?
Answer:
Phototropism is the growth movement in response to unidirectional stimulus of light. It is observed in plant stem, root, leaves. Stem is positively phototropic.

Question 3.
Write differences between nastic and tropic movements.
Answer:

	Nastic Movements	Tropic Movements
1. Growth	growth independent movements	growth dependent movements
2.Time of Action	immediate	slow
3. Response to Stimulus	Non-directional	directional
4. Reason for action	change in turgor	cell division
5. Alternate name	nastics	tropism
6. Examples	folding of leaves of touch me- not(Mimosa), opening and closing of stomata	phototropism, geotropism, hydrotropism, chemotropism

Question 4.
Why is pituitary gland called master endocrine gland?
Answer:
Pituitary gland is a small pea-shaped endocrine gland situated inferior to hypothalamus. It is called master endocrine gland because its secretion control and regulates the secretions of all other endocrine glands.

Question 5.
Name one disorder each in case of less (hypo) or excess (hyper) secretion of insulin and thyroxine.
Answer:

Name of hormone	Disorder due to hvposecietion	Disorder due to hypersecretion
Insulin	Diabetes	Hyperglycemia
Thyroxine	Myxedema	Exophthalmic goitre

Question 6.
List four uses of auxins.
Answer:
Functions of IAA

• IAA brings about cell elongation.
• It initiates the formation and growth of roots and stem if applied to the cutting of stem.
• Application of auxins causes formation of seedless fruits.
• It has an inhibitory effect on abscission of leaves and fruits, which lead to leaf fall and fruit drop.
• The parthenocarpy can be induced by application of auxins.
• Respiration rate increases with auxins.

Question 7.
What are the physiological effects of gibberellins?
Answer:
Physiological effects of gibberellins :

• Gibberellins promote cell-division.
• Gibberellins promote cell-elongation.
• Gibberellins lead to increase in the length of internodes.
• Gibberellins induce parthenocarpy in many cases e.g. tomato.
• Gibberellins promote flowering in some plants like Chrysanthemum.
• Gibberellins prevent senescence in leaves.

Question 8.
What are the functions of cytokinins?
Answer:
Functions of cytokinins

• It promotes cell division by activating DNA synthesis.
• It promotes the growth of lateral buds by neutralising the auxin.
• It is reported that cytokinin activates protein synthesis in buds by incorporation of labelled amino acid.
• It is also found to be effective in removing the apical dominance.

Question 9.
Write short notes on abscisic acid and ethylene.
Or
Write functions of abscisic acid.
Answer:
Abscisic acid (ABA)

• Abscisic acid (ABA) is a growth regulator found widespread in plants. It is a growth inhibitor.
• Abscisic acid causes the inhibition of mitosis in the vascular cambium.
• As the winter approaches, the ABA brings about the dormancy of axillary buds.
• Abscisic acid also induces the dormancy in seeds.
• It causes ageing in leaves. It is also called ‘stress hormone’.

Question 10.
Write functions of Ethylene.
Answer:
Ethylene:
Ethylene is synthesized in the plants from amino acid methionine. Ethylene produces the effect on the growth of vegetative and reproductive parts of the plant.

Ethylene is the only gaseous phytohormone. It is basically a growth inhibitor and brings about the following functions in the plant body.

• Ethylene inhibits root growth and development of lateral buds.
• Ethylene inhibits the elongation of stem and stimulates its transverse expansion.
• The changes which occur during the ripening of fruit are also attributed to the effect of ethylene.
• Ethylene also accelerates the process of ageing in plant organs.

Question 11.
What is chemotropism?
Answer:
Directional movement of a plant/ or its parts in response to chemicals is called chemotropism e.g. growth of the pollen tube towards the ovule is a chemotropic movement due to which fertilization of flower takes place.

Question 12.
Give examples of geotropism.
Answer:

• 1.Roots move in the direction of gravity (positive geotropism).
• Shoots move (up) against direction of gravity (negative geotropism).

Question 13.
What is the type of phenomenon shown in the figure? Define the same.

Answer:

• Geotropism:
• Geotropism. It is a type of growth movements induced by stimulus of gravity.

Question 14.
Differentiate between hormones and enzymes.
Answer:
Differences between hormones and enzymes

Hormones	Enzymes
1. They are produced by glands which lack ducts (endocrines).	1. They are generally produced by glands which bear the ducts (exocrine).
2. They may be steroids, amines or protein in chemical nature,	2. They are always proteinic in nature.
3. They are consumed during metabolism.	3. They act as catalysts and are produced in the same quantity at the end of reaction.

Question 15.
Briefly explain the autonomic nervous system.
Answer:

• Autonomic nervous system: The autonomic nervous system coordinates the activities of viscera through the regulation of their smooth muscles and glands by its nerves.
• The sympathetic nervous system prepares the body to face an emergency by accelerating heart beat and breathing rate; dilating the bronchioles to facilitate gas exchange; and sending blood to the organs which need it most such as heart, brain and skeletal muscle for “fight or flight”. It releases neurotransmitters adrenaline and noradrenaline into the synapses (adrenergic).
• The parasympathetic nervous system acts when body is relaxing after an emergency. It restores heart beat and respiratory rate to normal and restarts digestion. It releases acetylcholine into the synapses (cholinergic).

Question 16.
List different parts of the human nervous system.
Answer:

Question 17.
Define ‘nerve impulse’. Which structure in a neuron helps to conduct a nerve impulse?
(i) towards the cell body?
(ii) away from the cell body?
Answer:
Nerve impulse: The information passing through neurons in the form of electrical and chemical signals is called nerve impulse. Neurofibrils in the neuron help to conduct impulses.

Neuron is structural and functional unit of nervous system.

• Dendrite carries the impulse to cell body.
• Axon carries impulse away from cell body.

Question 18.
Name the five major senses of man.
Answer:
Five major senses of man

1. Sense of hearing.
2. Sense of smell.
3. Sense of touch.
4. Sense of taste.
5. Sense of vision or sight.

Question 19.
Write short note on meninges present around brain. Name the fluid present in the spaces in between meninges. Mention its function.
Answer:
Meninges (Sing. Meninx.) The protective membranes present around brain. They are as follows :

1. Duramater: It is outer, thick, non-vascular membrane present inner to bones of cranium.
2. Piamater: It is inner, thin, vascular membrane present closely around brain.
3. Arachnoid membrane: It is the middle membrane.
4. Cerebrospinal fluid is present in between the meninges. It protects brain from mechanical shock.

Question 20.
Label the parts of human brain.

Answer:
A. Cerebrum
B. Cerebellum
C. Medulla oblongata.

Question 21.
What is a gland? Name the two types of glands.
Answer:
Definition: A cell, a tissue, or an organ which secretes certain useful chemical compounds required for particular function is called a gland.

Types: Animals have two types of glands: exocrine and endocrine.

Question 22.
How does our body maintain blood sugar level?
Answer:
The timing and amount of hormone released are regulated by feedback mechanisms.
When the sugar levels in blood rise, they are detected by the cells of the pancreas which respond by producing more insulin. As the blood sugar level falls, insulin secretion is reduced.

Question 23.
Why is pancreas a dual gland?
Answer:
Pancreas is a dual gland because it acts as both endocrine and exocrine gland. As endocrine it secretes hormones like insulin, glucagon. As an exocrine gland, it releases enzymes like trypsin, lipase, amylase etc. Such types of glands are also called heterocrine glands.

Question 24.
List the functions of testosterone and estrogen.
Answer:

• Functions of testosterone: Develops male reproductive organs and secondary sexual characters in males.
• Functions of estrogen: Develops female genital organs and secondary sexual characters in females.

Question 25.
Name the hormones which stimulate the testis.
Answer:

• Follicular Stimulating Hormone (FSH). It stimulates the production of sperms in the testis.
• Interstitial Stimulating Hormone (ISH). It stimulates the interstitial cells of the testis and produce a male sex hormone known as ‘testosterone’.

The FSH and ISH are secreted by pituitary gland.

Question 26.
List some of the functions of adrenal glands.
Answer:
Functions of adrenal glands

• Prepare the body for emergencies.
• Regulate the kidney in maintaining salt and water balance.
• Control blood pressure and pulse rate.
• Control concentration of sodium, potassium and sugar in the body.
• Control some sexual characteristics.
• Influence breakdown of tissue proteins into amino acids.

Question 27.
Write a note on turgor movements.
Or
Mechanism of movements shown by Mimosa pudica, if touched.
Answer:
Turgor movements. Mimosa pudica (Touch-me-not) shows typical seismonastic type of movements. It is a paratonic variation type of movement which is brought about in response to external stimulus of touch. Leaf of Mimosa pudica is a compound leaf. It shows pulvini of primary and secondary order of petioles and sub-petioles. It gives a very quick response to a shock stimulus.

Question 28.
How do phototropism differ from geotropism?
Answer:
Differences between phototropism and geotropism

Phototropism	Geotropism
1. Response of parts of plants in the form of growth movement to the stimulus of light is called phototropism.	1. It applies to growth movements induced by stimulus of force of gravity.
2. Stem and aerial parts bend towards light source.	2. Stem and aerial parts move away from force of gravity.
3. Roots and other underground parts move away from source of light.	3. Roots and other underground parts move towards the force of gravity.

Question 29.
List the major endocrine glands and state their position in the human body.
Answer:
The major endocrine glands in the human body are:

• Pituitary gland
• Thyroid gland
• Parathyroid gland
• Thymus gland
• Islets of Langerhans present in Pancreas
• Adrenal gland
• Testis
• Ovary
• Pineal Gland.

Endocrine glands in human (a) male (b) female

Question 30.
Nervous and hormonal system together perform the function of control and co-ordination in human beings.” Justify the statement.
Answer:
Nervous and hormonal system. Both nerves and hormones transmit information between different parts in the animal body, in the same manner (chemical communication). Both coordinate and regulate physiological activities of the organisms. Moreover, there is a considerable coordination between the two. Synthesis and release of some hormones are regulated by nerves. On the other hand, hormones may also influence the activation of nerves. Because of their interrelationship, the nervous and the endocrine system are now together referred to as the neuroendocrine system.

Question 31.
What are the general functions of ‘hormones’?
Answer:
Functions of Hormones

• Hormones stimulate the tissue activity.
• Hormones regulate growth and reproduction.
• Hormones control metabolism.
• Hormones synthesize, store and utilize substances like glucose.
• Hormones conserve water and minerals.

Question 32.
Label 1 and 2 in the figure given below:

Answer:
1. Ovary
2. Neck showing location of Thyroid.

Very Short Answer Type Questions

Question 1.
Are movements in living organi-sms a characteristic of life?
Answer:
No.

Question 2.
Movements in plants are due to result of which kind of action?
Answer:
Growth.

Question 3.
Crying, respiration and voluntary movements are linked to which category.
Answer:
Involuntary actions.

Question 4.
Name the structural and functional unit of nervous system.
Answer:
Neuron.

Question 5.
What is the function of dendrites?
Answer:
Dendrites acquire the information.

Question 6.
Name the structure of neuron which conduct impulse.
Answer:
Axon.

Question 7.
Name the sites where electrical impulses are conducted into hemical impulses.
Answer:
Synapse.

Question 8.
What is a neuron?
Answer:
Neuron: It is a structural and functional unit of nervous system. It is the largest cell of the body.

It has three components i.e.

1. cell body
2. dendrites
3. axon.

Question 9.
What is synaptic cleft?
Answer:
The gap between dendrites of one neuron and axon of the next neuron is called synaptic cleft.

Question 10.
Mention the receptors for light and sound in animals.
Answer:

• Receptors for light. Photore-ceptors (Eyes)
• Receptors for sound. Phonoreeeptors (Ears)

Question 11.
What is reflex action?
Answer:
Reflex action: It is sudden spontaneous, mechanical, involuntary response to a stimulus by voluntary organs.

Question 12.
Give two examples of reflex action.
Answer:

1. Closing of eyes in response to bright light.
2. Withdrawal of hand in case touched a hot plate.

Question 13.
Which organ is involved in reflex action?
Answer:
Spinal cord.

Question 14.
Name three parts of neurons in complex reflex arc.
Answer:
A complex reflex arc is composed of afferent, connector and efferent neurons.

Question 15.
Name the main constituents of central nervous system.
Answer:
Brain and spinal cord.

Question 16.
What are the components of peripheral nervous system?
Answer:
Cranial (cerebral) nerves and spinal nerves originating from brain and spinal cord respectively.

Question 17.
Name the three main parts of brain.
Answer:
Fore brain, Mid brain and Hind brain.

Question 18.
List three involuntary actions.
Answer:
Circulation of blood, secretion of saliva and movement of food in the alimentary canal.

Question 19.
Involuntary actions are cont-rolled by which part of brain.
Answer:
Medulla.

Question 20.
Cycling, walking along a straight path and picking up of pencil are controlled by which part of brain.
Answer:
Cerebellum of hind brain.

Question 21.
Name the part of brain which control balancing and voluntary movements of body.
Answer:
Cerebellum of hind brain.

Question 22.
What is the function of cerebro spinal fluid?
Answer:
CSF (cerebrospinal fluid) acts as a shock absorber.

Question 23.
Name the structure which protects spinal cord.
Answer:
Vertebral column.

Question 24.
How does plant cell change its shape?
Answer:
Change in the water content of plant cell.

Question 25.
What is the function of tendril.
Answer:
Tendril helps in climbing along a support.

Question 26.
Name the hormone which help in cell division.
Answer:
Cytokinin.

Question 27.
Name the hormone secreted by adrenal gland.
Answer:
Adrenaline.

Question 28.
Where is thyroxine hormone secreted?
Answer:
Thyroid gland.

Question 29.
Name the hormone which plays role in metabolism of carbo-hydrates, proteins and fats.
Answer:
Thyroxine hormone.

Question 30.
Name the gland which secreted growth hormone.
Answer:
Pituitay gland.

Question 31.
Name the hormones which play role in maturity during adolescence in boys and girls.
Answer:
Testosterone in boys and estrogen in girls.

Question 32.
Where is insulin secreted?
Answer:
Pancreas.

Question 33.
In addition to nervous system, which other system plays role in coordination.
Answer:
Endocrine system which secretes chemical messengers called hormone.

Question 34.
Name the hormone which helps in chemical co-ordination in plants.
Answer:
Phytohormone (plant hormones).

Question 35.
What is the main element of thyroxine hormone?
Answer:
Iodine.

Question 36.
What is the main function of the vasopressin hormone?
Answer:
Regulates water content in the blood.

Question 37.
Write the function of hormone ‘thyroxine’ in our body.
Answer:
It regulates metabolism of carbo-hydrates, fats and proteins.

Question 38.
Which two systems of body work together for control and coordination of body parts?
Answer:
Nervous system and Hormonal system (endocrine glands).

Question 39.
Which organ secretes a hormone when the blood sugar rises. Name a digestive enzyme released by this organ.
Answer:

1. Pancreas releases insulin hormone.
2. Trypsin enzyme.

Question 40.
Define endocrine glands.
Answer:
These glands are ductless glands which secrete chemical messengers called hormones carried by blood to target organs.

Question 41.
Name the hormone which inc-reases blood pressure and rate of heart beat.
Answer:
Adrenaline.

Question 42.
Name the female sex hormones.
Answer:

• Progesterone
• Oesterogen
• Estardiol.

Question 43.
Name the following :
(i) The cause of diabetes mellitus.
Answer:
Deficiency of insulin

(ii) The two portions of adrenal gland.
Answer:
Adrenal cortex and adrenal medulla

(iii) The gland which function actively in emergency situations.
Answer:
Adrenal medulla

(iv) The hormone of pituitary that helps in child birth.
Answer:
Oxytocin

(v) The endocrine gland located on the top of kidneys.
Answer:
Adrenal gland

(vi) The gland which secretes insulin.
Answer:
Pancreas.

Question 44.
Name the following :
(i) The hormone which prepares the body to meet any emergency situation.
Answer:
Adrenaline

(ii) An example of the disease caused due to insufficient secretion of hormone.
Answer:
Cretinism

(iii) The gland, which produces the so called ‘emergency hormone’.
Answer:
Adrenal gland

(iv) Carrier of hormones from the gland to target organ.
Answer:
Blood

(v) The hormone which controls (i.e. reduces) the level of sugar in blood, and the gland which secretes it.
Answer:
Insulin, Pancreas.

Question 45.
Name the three kinds of neuron.
Answer:

1. Motor neuron
2. Sensory neuron
3. Relaying neuron.

Question 46.
What happens when bright light is focussed on eyes?
Answer:
Eyes get closed in response to light so as to protect the eyes.

Question 47.
Where are receptors located in the body?
Answer:
Sense organs.

Question 48.
What is the function of gustatory receptors?
Answer:
To taste the food.

Question 49.
Name the organs concerned with sense of smell.
Answer:
Olfactoreceptor.

Question 50.
Which part of plant bends towards light?
Answer:
Shoot apex.

Question 51.
Name the largest cell present in human body.
Answer:
Neuron.

Question 52.
What are the three basic regions of the brain?
Answer:

1. Fore brain
2. Mid brain
3. Hind brain.

Question 53.
Which part of the brain controls the heart?
Answer:
Medulla oblongata.

Question 54.
Name the following :
(i) Structural and functional units of the nervous system.
Answer:
Neurons

(ii) Two type of peripheral nerves.
Answer:
Cranial and spinal nerves

(iii) Most important part of the nervous system.
Answer:
Brain

(iv) Three divisions of human brain.
Answer:
Fore brain, mid brain and hind brain

(v) Largest part of the brain.
Answer:
Cerebrum

(vi) Two types of matter present in brain and spinal cord.
Answer:
White matter and grey matter.

Question 55.
How many hormones are secreted by pituitary gland?
Answer:
13 Types of hormones are secreted by pituitary gland.

Multiple Choice Questions

Question 1.
Which of the following is not a plant hormone?
(A) GA3
(B) Ethylene
(C) Phytochrome
(D) Auxins.
Answer:
(C) Phytochrome

Question 2.
Cytokinins stimulate the cell for:
(A) Turgor
(B) Elongation
(C) Cell division
(D) Wall thickening
Answer:
(C) Cell division

Question 3.
Movement in the leaf of the Touch-me-not (Mimosa) plant is:
(A) Epinasty
(B) Hyponasty
(C) Nyctinasty
(D) Seismonasty.
Answer:
(D) Seismonasty.

Question 4.
Hydrotropism is response towards:
(A) light
(B) touch
(C) gravity
(D) water.
Answer:
(D) water.

Question 5.
The reflex action is :
(A) blinking of eyelid
(B) swallowing of food bolus
(C) sneezing and coughing
(D) All the above.
Answer:
(D) All the above.

Question 6.
Nerve fibres transmit the nerve message by means of :
(A) chemical
(B) physical
(C) electrochemical
(D) electrical.
Answer:
(C) electrochemical

Question 7.
Brain and spinal cord act as :
(A) Receptors
(B) Effectors
(C) Modulators
(D) None of these.
Answer:
(A) Receptors

Question 8.
Which of the following is not a structure in the hind brain?
(A) Medulla oblongata
(B) Thalamus
(C) Cerebellum
(D) Pons.
Answer:
(B) Thalamus

Question 9.
Which one of the following endocrine gland produces two distinct hormones?
(A) Adrenal
(B) Thymus
(C) Testis
(D) Pineal.
Answer:
(A) Adrenal

Fill in the Blanks :

Question 1.
The nervous system uses ______ impulses to transmit messages.
Answer:
electrical.

Question 2.
______ is the main coordinating centre in the body.
Answer:
Brain.

Question 3.
The movement of a part of a plant in response to light is called ______
Answer:
Phototropism.

Question 4.
Endocrine glands secrete ______ into blood.
Answer:
Hormones.

Question 5.
Insulin hormone is secreted by ______
Answer:
Pancreas.

Question 6.
Auxins play role in cell ______
Answer:
Elongation.

Question 7.
In human there are ______ pairs of cranial nerves.
Answer:
Twelve.

Question 8.
______ is the junction between two adjacent neurons.
Answer:
Synapse.

Punjab State Board PSEB 9th Class Science Important Questions Chapter 5 The Fundamental Unit of Life Important Questions and Answers.

PSEB 9th Class Science Important Questions Chapter 5 The Fundamental Unit of Life

Long Answer Type Questions

Question 1.
Describe the structure of the plant cell.
Answer:
A generalized plant cell consists of three distinct parts viz, cell wall, cell membrane or plasma membrane and protoplasm.
1. Cell wall. It is the outermost covering of a cell made up of a non-living substance called cellulose. Is is permeable. It provides shape, strength and protection to cell.

2. Cell membrane or Plasma membrane. It is thin, delicate and elastic protoplasmic covering lying internal to the cell wall. The plasma membrane controls the entrance and exit of molecules and ions.

3. Cytoplasm. It consists of a number of living and non-living structures. The living structures are called cytoplasmic organelles or cell organelles and include structures like endoplasmic reticulum, ribosomes, golgi apparatus, mitochondria, lysosomes, plastids, vacuoles etc.
(a) Plastids. Plastids are spherical or discoid bodies containing different types of pigments in them. They are of three types viz. chloroplasts, chromoplasts and leucoplasts. The chloroplasts contain a green pigment in them, called chlorophyll. They play a vital role in the process of photosynthesis. The chromoplasts contain pigments other than chlorophyll. They impart various colours to flowers and fruits. Leucoplasts are colourless plastids. They are concerned with the storage of starch.
(b) Mitochondria are power house of cell.
(c) Ribosomes are of 70 S type. They are site for protein synthesis.
(d) Endoplasmic reticulum is network of membranes.
(e) Vacuoles. These are fluid-filled bubble-like structures bounded by a membrane, called tonoplast. They are mostly found in plant cell. Vacuoles provide turgidity and rigidity to cell.

4. Nucleus. It is a dense spherical body bounded by a membrane, called nuclear membrane. Embedded within the nuclear sap are found a number of thread-like structures called chromosomes with genes on them. The nucleus controls the various metabolic activities of the cell.

Question 2.
Draw a well labelled diagram of ultrastructure of plant cell.
Answer:
Ultrastructure of plant cell

Question 3.
Describe the structure of nucleus. Write its functions.
Answer:
A true nucleus is present in all the eukaryotic cells except mammalian RBCs, sieve tube cells, tracheids and vessels. It directs life processes of cells. It is formed of four components:
(a) Nuclear membrane. It is a two-layered envelope around the nuclear sap. It is porous (with nuclear pores) and semipermeable membrane. Outer membrane is studded with ribosomes and may be continuous with RER. It regulates exchange of materials between nucleoplasm and cytoplasm.

(b) Nucleoplasm. It is a semifluid colloidal substance in which nucleoli and chromatin fibres are present.
(c) Nucleolus. It is dense, spherical, naked and darkly stained structure and is the site of formation and storehouse of rRNAs.
(d) Ovomatin 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 species-specific number of rods, called chromosomes. These are with genes which are chemically formed of DNA and act as units of heredity and variations.
Functions of the nucleus:
The nucleus performs the following important functions:

• The nucleus controls all the cellular activities of the cell.
• Tire nucleus plays an important role in transmission of hereditary characters from parents to offsprings.
• The nucleus plays a vital role in cell division.

Question 4.
Write short notes on:
(a) Chloroplast
(b) Endoplasmic reticulum
(c) Golgi bodies
Answer:
Structure and functions of a chloroplast:
A chloroplast is formed of two membranes and two chambers, so resembles a mitochon-drion. Outer membrane is freely permeable while inner membrane is semi permeable. Inner chamber is filled with a denser and granular proteinaceous (about 50%) ground substance called stroma or matrix. It is site of dark reaction or CO₂ fixation of photosynthesis and has a number of grana, 70 S ribosomes and DNA molecules (circular and naked).
1. Grana are site for light reactions of photosynthesis.
2. Function of Chloroplasts: These are sites of photosynthesis, so are called “kitchens of cell.”

(b) Endoplasmic reticulum
There are two forms of endoplasmic reticulum. They are the following:

• Rough type (RER): Ribosomes are associated with rough endoplasmic reticulum.
• Smooth type (SER): Golgi apparatuses are associated with smooth endoplasmic reticulum.

Components of ER

Functions of Rough and Smooth Endoplasmic reticulum

Functions of Endoplasmic Reticulum:

1. The endoplasmic reticulum acts as secretory, storage, circulatory and nervous system of the cell. Its functions depend upon its location, nature and cell type.
2. It provides an ultrastructural skeletal framework of the cell.
3. ER provide channels for quick transport of materials.
4. It provides surface for attachment of ribosomes.
5. It provides materials, lipids and proteins for biogenesis of membranes.

Functions of Smooth Endoplasmic Reticulum:

1. Detoxification of drugs and poison.
2. Formation of visual pigment from Vitamin A in retinal cells.
3. Synthesis of fats inside the cells of adipose tissue.
4. Synthesis of steroids and hormones.

(c) Golgi complex or Golgi Apparatus:
The golgi complex is usually located near the cell nucleus and in animal cells it is frequently disposed around the centriole pair. It normally consists of numerous sets of membrane-bound, smooth surface cisternae. Each cisterna is flat, disc-shaped and curved like a shallow bowl.

It has lumen which is bounded by a single membrane. Each set of flattened disc-shaped cistemae forms a structure that resembles stack of plates, called a Golgi stack or dictyosome (as referred in the plants).

Question 5.
Discuss the structure and function of mitochondrion.
Answer:
Structure. Mitochondria are ‘power house’ of cells. It has two mitochondrial membranes and two chambers. Outer mitochondrial membrane is smooth and porous while inner mitochondrial membrane is produced into finger-like processes called cristae to increase the surface area for the distribution of respiratory enzymes of electron transport chain.

Cristae are studded with regularly placed knob-like oxysomes which take part in energy releasing reactions. Inner chamber is filled with a granular matrix having respiratory enzymes. Matrix present in inner chamber also contains DNA, RNA and ribosomes.

Functions of mitochondria:

1. These are called power houses or power plants or ATP mills as these are site of aerobic oxidation (cellular respiration) of glucose to produce energy-rich ATP molecules.
2. They provide biological intermediates for the synthesis of various biomolecules such as fatty acids, amino acids, steroids etc.

Question 6.
Write a note on prokaryotic cell.
Answer:

1. The prokaryotes have a single membrane.
2. Cells which have respiratory enzymes associated with plasma membrane.
3. Circular DNA without proteins, forming a single prochromosome called nucleoid and lying in direct contact with cytoplasm.
4. They have 70 S ribosomes.
5. They lack membrane-bound organelles and sap vacuoles.
6. They do not show cyclosis, phagocytosis, pinocytosis and exocytosis.
7. Cell division by fission or budding.
8. Examples. Bacteria, Blue green algae and Mycoplasma.

Question 7.
Write a short note on eukaryotic cell.
Answer:

1. The eukaryotic cells have double membrane and plasma membrane devoid of respiratory enzymes.
2. These cells have linear DNA associated with proteins forming two to many chromosomes enclosed by a nuclear envelope. Thus proper well defined nucleus is present.
3. There are present 80 S ribosomes.
4. Many membrane-bound organelles such as mitochondria, chloroplasts, lysosomes etc., and sap vacuoles present.
5. Form mitotic apparatus in cell division and undergo meiosis.
6. They may show cyclosis, phagocytosis, pinocytosis and exocytosis.

Question 8.
Draw the ultrastructure of a typical animal cell.
Answer:
An animal cell has three functional regions. Plasma membrane, cytoplasm and nucleus.

Short Answer Type Questions

Question 1.
What is cell and cell theory?
Answer:
Cell. 1. Structural and functional unit of life is called cell.
2. A cell is mass of protoplasm formed of different types of inorganic and organic biomolecules and externally bounded by a thin and semipermeable plasma membrane.
Cell Theory. M.J. Schleiden and Theodore Schwann (1938-39) proposed cell theory. The cell theory can be stated as follows:
(a) The body of all living organisms is composed of cells. Cell is a unit of structure and function of life.
(b) New cells are formed from the pre-existing cells only (R. Virchow).
(c) The life is passed from one generation to the next generation through a single cell.

Question 2.
What is a prokaryotic cell?
Answer:
Prokaryotic cell, (pro = primitive, karyon = nucleus) It is characterized by an incipient nucleus called nucleoid formed of single and circular chromosome. It is formed of double-stranded DNA but not associated with histone proteins. It is not enclosed by nuclear membrane.

• Membrane-bound cell organelles such as mitochondria, chloroplasts etc. are absent.
• Examples: Bacteria, Blue-green algae, Mycoplasma etc.

Question 3.
What is a eukaryotic cell?
Answer:
A eukaryotic (eu = good; karyon = nucleus) cell has true nucleus which has two or more linear chromosomes lying in the nucleoplasm and is surrounded by a double and porous nuclear membrane. Membrane bound organelles present. 80 S Ribosomes present (S = Svedberg unit).

Question 4.
Explain structural and functional organisation of unicellular and multicellular organism.
Answer:

• Unicellular organism, in such organisms, a single cell carries out all life processes with the help of organelles. They are also called acellular organisms.
• Multicellular organism. A multicellular organism is made up of large number of cells.
• The cells are differentiated to share varied functions performed by unicellular organisms. Whatever the case may be, all multicellular organisms start their life from a single cell.
• The multicellular organism represents itself in two forms – as an individual and as a member of assembly of cells.
• Advantages of Multicellularity:
  • The division of labour in a multicellular organism increases the efficiency of the organism.
  • It promotes the chance of survival.

Question 5.
What do you mean by:
1. Organelle
2. Inclusions
Answer:
1. Organelle, it is a living structure of cell with a specific function.
2. Inclusions. The lifeless structures in a cell, which may or may not have a definite function are called inclusions. These are vacuoles, excretory products, starch grains etc.

Question 6.
Distinguish between cell wall and cell membrane.
Answer:
Differences between cell wall and cell membrane

Cell wall	Cell membrane
1. It is present only in plant cells where it lies outside the cell membrane. 2. Dead in nature and permeable. 3. Composed of cellulose. 4. It is thick in nature.	1. It ocurs in animal cells and plant cells. 2. Living membrane and is semi-permeable. 3. Composed of lipids and proteins. 4. Comparatively very thin.

Question 7.
Name the two nucleic acids present in cell.
Answer:

• DNA (Deoxyribose nucleic acid): It is the genetic material. It is passed on from parents to next generation, It regulates the functioning of cells.
• RNA (Ribose nucleic acid): It is structural component of ribosome. It plays role in protein systhesis.

Question 8.
Why are mitochondria called “power house of cell”?
Answer:
Mitochondria are site of generation, transport and storage of ATP. Adenosine triphosphate (ATP) is the energy currency of the cell.

Question 9.
Explain lysosomes.
Answer:

• Lysosomes. They are single membrane bound vescicular structures. They are present in cytoplasm of eukaryotic cells. They contain digestive enzymes.
• They exist in four different forms thus exhibit polymorphism.
• They are involved in autolysis and hence called as ‘suicidal bags.’

Question 10.
List the functions of vacuoles.
Answer:
Functions of vacuoles

1. They act as storage sacs for solid or liquid contents of cell.
2. They help the cell to remain turgid and rigid.
3. Vacuoles play an important role in growth.
4. In some freshwater unicellular organisms, specialised vacuoles play an important role in expelling excess water and some wastes from, cells. It is called osmoregulation.

Question 11.
What is centrosome? List two functions of centrosome.
Answer:
Centrosome: It consists of granule like two centrioles; surrounded by clear area of cytoplasm called centrosphere. It is present in animal cells only.
Functions of centrosome:

• They help in spindle formation during cell divison in animal cell.
• They act as basal bodies and give rise to motile structures, i.e. cilia and flagella.

Question 12.
Differentiate smooth endoplasmic reticulum (SLR) and rough endoplasmic reticulum (RER).
Answer:
Differences between SER and RER:

SER	RER
1. It does not bear ribosomes over the surface of its membranes which are smooth. 2. It is engaged in the synthesis of glycogen, lipids and steroids. 3. It gives rise to sphaerosomes.	1. It possesses ribosomes attached to its membranes which are rough. 2. The reticulum takes part in the synthesis of proteins and enzymes. 3. It helps in the formation of lysosomes through golgi apparatus.

Question 13.
What are ribosomes? Write their kinds and chemical composition.
Answer:
Structure of Ribosome. The ribosomes are ribonucleoproteinic, obovate, spheroid without membrane structures. They are having two sub-units, one is larger sub-unit having dome-shaped structure and the other smaller sub-unit forming a cap-like structure. They are composed of ribosomal RNA (rRNA) and proteins.
Type of ribosomes:
1. 70 S ribosomes. They are present in both prokaryotic and eukaryotic cell.
2. 80 S ribosomes. They are present in eukaryotic cell.

Functions of ribosomes:
They are the site of protein synthesis as they contain enzymes involved in protein synthesis.

Question 14.
Write functions of cell wall.
Answer:
Functions of cell wall:

1. It provides shape and rigidity to the cell
2. It protects the protoplast.
3. It permits cells of bacteria, fungi and plants to withstand very dilute external environment without bursting.
4. It increases the size of cell by continuous absorption.
5. It is involved in the movement of materials in and out of the cell.

Question 15.
Give the functions of plasma membrane.
Answer:
Functions of plasma membrane:

1. It maintains individuality of cells.
2. It provides shape to the cell.
3. It keeps the cell contents in place and distinct from the environmental materials.
4. It protects the cell from injury.
5. It regulates the flow of material into and out of the cell. It allows only the selected substances to move across it.
6. It forms organelles of cell.

Question 16.
Define the following:

1. Cytoplasm
2. Hyaloplasm
3. Nucleoplasm.

Answer:

1. Cytoplasm: The clear, translucent, colourless, viscous, fluid in which are present various cell inclusions and organelles is called cytoplasm.
2. Hyaloplasm: The clear homogeneous ground substance of cytoplasm is termed hyaloplasm (cytoplasmic matrix).
3. Nucleoplasm: Clear transparent homogeneous fluid inside the nucleus is called ucleoplasm.

Question 17.
State the differences between cilia and flagella.
Answer:
Differences between cilia and flagella:

Cilia	Flagella
1. They are short hair-like structures with an average length of 5-10 mm. 2. They are present all over the surface of cell of the organism. 3. They are more in number usually 100 to a few thousand per cell. 4. They beat perpendicularly and simultaneously. 5. The cilia produce a sweeping or pendular stroke.	1. They are long, whip-like structures with an average length of 150 mm. 2. They are usually present on one end of cell. 3. They are less in number usually 1 or 2 per cell. 4. They beat freely. 5. The flagella produce undulatory motion.

Question 18.
State the differences between grana and stroma.
Answer:
Differences between grana and stroma:

Grana	Stroma
1. It consists of flatfened sac-like structures which are piled up one above the other like stacks of coins. 2. They contain photosynthetic pigments on them. 3. They are made of lipoproteins.	1. It is matrix or ground substance of chloroplast in which different structures like grana and lamellae are embedded. 2. Pigments are absent. 3. It is composed of watery proteinaceous substance.

Question 19.
Write functions of cell wall.
Answer:
Function of cell wall:

1. It protects the cell from mechanical damage and infection.
2. It helps in cell-to-cell interaction.
3. It acts as a barrier to unwanted molecules.
4. It provides rigidity and mechanical support to the cells.

Question 20.
How will you examine cells of onion peel.
Answer:
Examination of Onion Feel

1. Take out the onion peel from the inner side of the scale of the bulb.
2. Put this transparent peel into water and cut a small piece.
3. Stain it with safranin solution. It will make the nucleus more distinct.
4. Put it on the slide and place it in glycerine.
5. Observe under low power microscope, then change it to high power and study the following:

Observation:

• Regular, rectangular-shaped cells are placed close to each other.
• Cell has a prominent cell wall, cytoplasm and nucleus. The vacuole occupies the central position.

Question 21.
What are possible shapes of cells? Explain with simple sketches.
Answer:
Shapes of cells

1. Shapes of the cells differ not only in different organisms but also in different parts of same organism. They may be oval, spherical, discoid, cuboidal, columnar, spindle-shaped etc.
2. The shape of the cell is usually related with its function.
3. Some other factors controlling the shape of cell are function, age, pressure, cell wall and internal or external skeleton.
4. Amoeba and leucocytes go on changing their shapes to enable them to engulf the materials.

Question 22.
Differentiate between diffusion and osmosis
Answer:
Differences between diffusion and osmosis:

Diffusion	Osmosis
1. Diffusion is the net downward movement of a given substance (ions, atoms or molecules, etc.) along the free energy gradient from the place of its higher concentration to an area of its lesser concentration. 2. The diffusion may occur in any medium and the diffusing particles may be solid, liquid or gas. 3. Presence of semipermeable membrane is not required.	Osmosis is a special type of diffusion of solvent molecules from low concentration of solution to higher concentration of solution when the two are separated by a semipermeable membrane. 2. The osmosis occurs in liquid medium and only the solvent molecules move from one place to another. 3. Presence of semi-permeable membrane in between the two solutions is required.

Question 23.
Which organelle is called as protein factory of the cell?
Answer:
Ribosomes provide space for the synthesis of proteins in the cell. Hence, they are called protein factories. It synthesises various proteins and enzymes for the cell. Haemoglobin is an example of a protein made by free ribosomes in the young red blood corpuscles.

Question 24.
Differentiate Ribosome and Lysosome.
Answer:
Differences between ribosome and lysosome:

Ribosome	Lysosome
1. Ribosome is an oval to rounded granular structure which is not covered ever by any membrane. 2. It consists of two unequal nucieoprotein subunits. 3. It takes part in protein synthesis.	1. Lysosome is a rounded membrane lined vesicle containing number of hydrolytic enzymes. 2. It does not consists of nucieoprotein. 3. It takes part in digestion, scavenging and defence against pathogens.

Question 25.
What are plastids? Name its three types.
Answer:
Plastids. These are double membrane bound organelles found in plant cell. These are of three types:

• Chromoplasts
• Chloroplasts
• Leucoplasts.

Question 26.
Write functions of plastids.
Answer:
Functions of plastids

1. Chloroplasts are the site of photosynthesis so called as kitchen of the cell.
2. Chromoplasts provide colour to flowers and fruits.
3. Leucoplasts are site of storage of food.
4. Granum is site of light reaction, while stroma is the site of dark reaction.

Question 27.
What are the functions of lysosomes?
Answer:
Functions of lysosomes:

1. Take part in intracellular digestion of foreign particle.
2. They provide energy during starvation.
3. They help in defence against bacterial and viral infection.
4. Lysosome removes cellular debris.

Question 28.
Name the various organelles of cell and mention the most important function of each.
Answer:
Names and functions of cellular organelles:

Name of cell organelle	Function
1. Plasma membrane	Protects the cell organelles and separates the contents of cell from external environment.
2. Cell wall (plant cell only)	Provides strength and rigidity to the cell. It permits the bacterial and plant cells to withstand very dilute external medium without bursting.
3. Cytoplasm	Contains machinery and metabolites for carrying out the instructions sent from nucleus.
4. Cytoplasmic matrix	Contains raw materials and enzymes for metabolism.
5. Endoplasmic reticulum	It is responsible for transportation of extracellular and intracellular chemical molecules. It is also the site for synthesis of various molecules.
6. Ribosomes	These are sites for protein synthesis.
7. Golgi complex	Complexing, packaging and dispatching various materials to various targets inside and outside the cells.
8. Mitochondria	Site for respiratory reactions and energy liberation in the form of ATP.
9. Lysosomes (animal cells only) Centrosome (animal cells only) Plastids (plants only). Cilia and flagella. Vacuoles. Nucleus.	Helps in waste disposal system and autolysis. Forms spindle during cell division. Responsible for photosynthesis. Provide movement to cell. Storage sacs for liquid and solid contents. Regulates growth and reproduction of cell.

Question 29.
Differentiate cytoplasm and nucleoplasm.
Answer:
Differences between cytoplasm and nucleoplasm

Cytoplasm	Nucleoplasm
1. Part of protoplasm that lies outside	1. Part of protoplasm that lies inside the
2. It appears to be homogeneous semi-fluid jelly-like substance	2. It is transparent.
3. It contains number of inorganic substances forming clear true solution and organic substances lipids, protein and carbohydrates forming a polyphasic colloidal system.	3. Nucleoplasm is colloidal substance having similar composition to cytoplasm, but contains more of nucleo- tides.
4. Suspended in it are various organelles and inclusions.	4. Suspended in it is chromatin.

Question 30.
What will happen to a cell if its nucleus is removed?
Answer:
Cell will die with passage of time as nucleus is the controlling centre of all functions of cell.

Very Short Answer Type Questions

Question 1.
What is the structural and functional unit of life?
Answer:
Cell.

Question 2.
Name three functional regions of a cell.
Answer:

• Plasma membrane
• Nucleus
• Cytoplasm.

Question 3.
Name the orgnelles present in the cells.
Answer:
Mitochondria, Ribosomes, Endoplasmic Reticulum, Golgi bodies, Centrosome, Lysosomes, Plastids.

Question 4.
Name the organelle present in plant cell only.
Answer:
Plastids.

Question 5.
What is the main component of nucleus?
Answer:
Chromatin network which takes up the shape of chromosomes at the time of cell division.

Question 6.
Give six examples of single celled organisms.
Answer:
Paramecium, Amoeba, Chlamydomonas, Euglena, Trypanosoma and Malarial parasite.

Question 7.
Who coined the term ‘Protoplasm’ for the fluid substance of cell?
Answer:
Purkinje (1839).

Question 8.
How it was made possible to observe the complex structures of cell?
Answer:
Discovery of electron microscope.

Question 9.
Name the organelle which takes part in protein synthesis.
Answer:
Ribosomes.

Question 10.
Which is the longest cell in plants.
Answer:
Sclerenchyma.

Question 11.
Name the smallest and largest cells.
Answer:

• Smallest cell – Mycoplasma.
• Largest cell-Ostrich egg.

Question 12.
Name the smallest and largest cell of human body.
Answer:

• Smallest cell – of kidney.
• Largest cell-neuron (nerve cell).

Question 13.
List the factors which denote size of cell.
Answer:

1. Structure
2. Location
3. Function.

Question 14.
What are the two main components of protoplasm?
Answer:
Cytoplasm and nucleoplasm.

Question 15.
Which cell organelle is called suicidal bag?
Answer:
Lysosome.

Question 16.
What is the primary function of lysosome?
Answer:
A centre of intracellular digestion, so is called digestive bag.

Question 17.
Name the cell organelle responsible for protein synthesis.
Answer:
Ribosomes.

Question 18.
Expand DNA.
Answer:
Deoxyribose nucleic acid.

Question 19.
Expand RNA.
Answer:
Ribose nucleic acid.

Question 20.
Who examined thin slice of cork under microscope?
Answer:
Robert Hooke.

Question 21.
What is cork?
Answer:
Cork is obtained from the bark of a tree.

Question 22.
Who coined the term cell?
Answer:
Robert Hooke.

Question 23.
Who examined the living cells for first time?
Answer:
A.V. Leeuwenhoek.

Question 24.
What are unicelluar organisms?
Answer:
The organisms formed of single cell e.g. Amoeba.

Question 25.
What are multicellular organisms?
Answer:
The organisms formed of a large number of cells are termed as multicellular organisms e.g. human beings.

Question 26.
Write examples of multicellular organisms.
Answer:
Fungi, plants and animals.

Question 27.
Write two features of cells of onion peel.
Answer:
Presence of cell wall and large central vacuole.

Question 28.
What is the contribution of Robert Brown in cell biology?
Answer:
Discovered nucleus in the cells of orchid.

Question 29.
What are the two types of cells on the basis of nature of nucleus? *
Answer:
Prokaryotic and Eukaryotic cells.

Question 30.
Name any two prokaryotic cells.
Answer:

• Bacterial cell
• Blue-green algae

Question 31.
Who proposed the cell theory?
Answer:
M.J. Schleiden and Theodore Schwann.

Question 32.
What is cell theory?
Answer:
All plants and animals are made up of cells and cell is the structural and functional unit of life.

Question 33.
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 34.
What is the number of cells present in an adult person?
Answer:
100 trillion (1014).

Question 35.
Which is the smallest measuring unit in the field of cell biology?
Answer:
Angstrom (A).

Question 36.
In which year electron microscope was invented?
Answer:
1940.

Question 37.
What is the nature of plasma membrane?
Answer:
It is formed of lipids and proteins.

Question 38.
Give the primary function of plasma membrane.
Answer:
It regulates exchange of materials between the cytoplasm and extracellular fluid.

Question 39.
Give one term for a semifluid ground substance present between plasma membrane and nucleus.
Answer:
Cytoplasm.

Question 40.
What is diffusion?
Answer:
Diffusion. The movement of substance from a region of higher concentration to a region of lower concentration is called diffusion.

Question 41.
What is the term for movement of water into and out of cell across a semipermeable membrane?
Answer:
Osmosis.

Question 42.
Define plasmolysis.
Answer:
Loss of water from a plant cell resulting in shrinkage or contraction of cell away from cell wall.

Question 43.
Give the common name of the mitochondria.
Answer:
Powerhouses or ATP mills.

Question 44.
Expand ATP.
Answer:
ATP. Adenosine triphosphate

Question 45.
Name two semi-autonomous cell organelles.
Answer:
Mitochondria and plastids.

Question 46.
Which type of enzymes are located inside the mitochondria?
Answer:
Respiratory enzymes.

Question 47.
Name the largest-sized cell organelle.
Answer:
Plastid (chloroplast).

Question 48.
Name three types of plastids.
Answer:
Leucoplasts, chloroplasts and chromoplasts.

Question 49.
Which cell organelle is called kitchen of cell and why?
Answer:
Chloroplast. It is site of photosynthesis in green plants. During this process plant prepare their own food by trapping solar energy and use COz and water as raw materials.

Question 50.
What are chromoplasts?
Answer:
These are coloured plastids with yellow, orange or red coloured plastids.

Question 51.
Write the chemical composition of cell wall.
Answer:
Cellulose.

Question 52.
What is the role of cell wall?
Answer:
Cell wall provide structural support to plant cell.

Question 53.
Which chemical is used to strain plant cell?
Answer:
Iodine, Safranin, methylene blue.

Question 54.
Give one major difference between SER and RER.
Answer:
SER is without ribosomes and is involved in lipid synthesis, while RER is with ribosome-studded cistemae and is involved in protein synthesis.

Question 55.
List two general functions of ER.
Answer:

• ER acts as channels for transport of materials within the cell.
• It also act as cytoskeleton.

Question 56.
Write one function of SER.
Answer:
Detoxification of many poisons and drugs.

Question 57.
Give the primary function of Golgi body.
Answer:
Cell secretion and acts as condensation membrane.

Question 58.
Which plastids are involved in storage of food?
Answer:
Leucoplasts.

Question 59.
What is the main difference between cell organelles and cell inclusions?
Answer:
Cell organelles are living structures of cytoplasm, while cell inclusions are non-living structures of cytoplasm.

Question 60.
Name the vacuolar membrane.
Answer:
Tonoplast.

Question 61.
Why is nucleus called director of cell?
Answer:
It controls and directs all the cellular activities.

Question 62.
Which organelle plays central role in cellular reproduction?
Answer:
Nucleus.

Question 63.
What is nature of nuclear membrane?
Answer:
It is two-layered, lipoproteinaceous, porous and semipermeable.

Question 64.
What is primary function of nuclear membrane?
Answer:
Regulates exchange of materials between nucleoplasm and cytoplasm.

Question 65.
What are the functional units of chromosomes?
Answer:
Genes.

Question 66.
What is the chemical nature of a chromosome?
Answer:
DNA and basic protein histones, so is called Deoxyribonucleoprotein (DNP).

Question 67.
Give the primary function of DNA of chromatin fibre.
Answer:
DNA acts as genetic material and helps in transmission of characters from par¬ents to offsprings.

Question 68.
What is the function of vacuole in plant cell?
Answer:
Vacuoles are full of cell sap and provide rigidity and turgidity to cell vacuoles, temporarily stores wastes.

Question 69.
Write functions of contractile vacuole in plant cell.
Answer:
Osmoregulation and expelling wastes from the cell.

Question 70.
Name the organelle which contains chlorophyll.
Answer:
Chloroplast.

Question 71.
What are two functions of plasma membrane?
Answer:

• Provides shape to cell
• Keeps intact the contents of cell.

Question 72.
What is osmosis?
Answer:
It is a special type of diffusion of solvent molecules from low concentration of solution to higher concentration solution separated by semipermeable membrane.

Punjab State Board PSEB 9th Class Science Important Questions Chapter 4 Structure of the Atom Important Questions and Answers.

PSEB 9th Class Science Important Questions Chapter 4 Structure of the Atom

Long Answer Type Questions:

Question 1.
What is Rutherford’s ∝-ray scattering experiment? Give its observations. How does Rutherford explain this observation?
Answer:
Rutherford’s ∝-ray scattering experiment: In this experiment, Rutherford obtained a thin stream of fast-moving alpha (∝) particles from radioactive source (P₀) and was allowed to strike against a thin foil of heavy metal like gold. Alpha particles are also called helium nuclei (He²⁺ with + 2 unit charge and 4 a.m.u. mass). As a result of the experiment, he made the following observations:

1. Most of the ∝-particles passed through the gold foil without any deflection from their original path.
2. Some of the ∝-particles got deflected by small angles from their original path.
3. A few ∝-particles (approximately 1 out of 10,000) were deflected to a large extent. In some cases, the a-particles came back in the same direction after striking the gold foil.

Explanation for the observations:

We know that the gold foil is made up of atoms of gold which are placed side by side. Since most of the ∝-particles passed through these atoms undeflected they did not come across any obstruction in their path, this shows that most of the space in the atom is light or hollow.

The electrons with negligible mass were supposed to be present in this portion called extra nuclear portion. The a-particies were deflected from their path and a very few came back in the same direction. This shows that they must have met with some obstruction in their path.
The obstruction must be
1. Heavy because a-particles are high speed particles and can remove light obstruction from their path.
2. Small because only a few a-particles got deflected.
3. Positively charged because some a-particles were repelled by this obstruction.

This small, heavy and positively charged portion inside an atom was called nucleus. The protons with mass and positive charge were supposed to be present in the nucleus. Later on, neutrons were also found to be present in the nucleus of the atom.

Question 2.
Discuss in brief Rutherford’s Model of atom.
Answer:
The main points of Rutherford’s model of atom are listed as follows:
1. An atom has two parts. These are nucleus and extra nuclear portion.
2. The nucleus contains protons while electrons are present in the extra nuclear portion.
3. Most of the mass of the atom is due to the nucleus because electrons have negligible mass.

4. The volume occupied by the nucleus is very small as compared to the volume occupied by extra nuclear portion.
5. The electrons in the extra nuclear portion are not stationary. These are revolving around the nucleus. The electrons are called planetary electrons because they can be compared to various planets which revolve around the sun. The nucleus may be compared with the sun.

Question 3.
Discuss the arrangement of the electrons in the different energy levels.
Or
Describe Bohr-Bury scheme for the distribution of electrons in the various orbits or energy levels of an atom.
Answer:
The distribution of electrons in the energy levels is given with the help of Bohr Bury scheme. It is given as follows:
1. The energy levels or energy shells are filled in order of increasing energies. The electrons first enter the K shell (n = 1. which is closest to the nucleus. This is followed by L shell (n = 2), M shell (n = 3) and so on. Here V represents the number of the shell.
2. The maximum number of electrons in any shell is given as 2n² (n = number of the shell). The distribution in the first four energy shells is given in the table given below:
Distribution of electrons in first four energy shells according to 2n² rule.

Symbol of shell	Number of shell (n)	Maximum number of electrons (2n2)
K	1	2 x (1)2 = 2
L	2	2 x (2)2 = 8
M	3	2 x (3)2 = 18
N	4	2 x (4)2 = 32

3. The outermost energy shell cannot have more than 8 electrons. The next inner shell called penultimate shell, cannot have more than 18 electrons.
4. It is not necessary that an energy level or shell is fully filled before the filling in the next energy level starts. In fact, filling of electrons in a new shell starts when any shell contains 8 electrons.
On the basis of the above scheme, let us discus with mass number 24 and atomic number 12.

• Mass no. of atom (A) = 24
• Atomic no. of atom (Z) = 12
• No. of protons in nucleus = 12
• No. of neutrons in nucleus = 12
• No. of electrons to be distributed = 12
• The distribution in the various energy shells: K L M: 2, 8, 2

Question 4.
Give the electronic distribution in the first twenty elements on the basis of Bohr-Bury scheme.
Answer:
On the basis of Bohr-Bury scheme, the distribution of electrons in first twenty elements (Z = 1 to Z = 20) is given below:
Table: Electronic distribution in atoms of first 20 elements

Element (Symbol)	Mass No. (A)	Atomic No. (Z)	No. of Protons (P)	No. of Electrons (e)	No. of Neutrons (n) (A-Z)	Electronic Distribution
						K	L	M	N
1. Hydrogen (H)	1	1	1	1	0	1
2. Helium (He)	4	2	2	2	2	2
3. Lithium (Li)	7	3	3	3	4	9	1
4. Beryllium (Be)	9	4	4	4	5	2	2
5. Boron (B)	11	5	5	5	6	2	3
6. Carbon (C)	12	6	6	6	6	2	4
7. Nitrogen (N)	14	7	7	7	7	2	5
8. Oxygen (O)	16	8	8	8	8	2	6
9. Fluorine (F)	19	9	9	9	10	2	7
10. Neon (Ne)	20	10	10	10	10	2	8
11. Sodium (Na)	23	11	11	11	12	2	8	1
12. Magnesium (Mg)	24	12	12	12	12	9	8	2
13. Aluminium (Al)	27	13	13	13	14 ‘	2	8	3
14. Silicon (Si)	28	14	14	14	14	2	8	4
15. Phosphorus (P)	31	15	15	15	16	2	8	5
16. Sulphur (S)	32	16	16	16	16	2	8	6
17. Chlorine (Cl)	35	17	17	17	18	2	8	7
18. Argon (Ar)	40	18	18	18	22	2	8	8
19. Potassium (K)	39	19	19	19	20	2	8	8	1
20. Calcium (Ca)	40	20	20	20	20	2	8	8	2

Special cases of Potassium and Calcium:

• In case of Potassium (Z = 19), the M shell has only 8 electrons and not 18. Actually, when the M shell gets 8 electrons, the filling of electrons starts in the next shell which is N-shell. When the N-shell gets 2 electrons, the electron are again- filled in the M shell.
• Thus, electronic distribution in potassium (Z = 19) is
  K L M N
  2 8 8 1 (M shell has 8 electrons and N shell has 1 electron)
• Similarly, the electronic distribution in calcium (Z = 20) is:
  K L M N: 2 8 8 2 (M shell has 8 electrons and N shell has 2 electrons)

Question 5.
Define the terms:

1. Atomic number
2. Mass number
3. Atom
4. Ion
5. Element
6. Orbit
7. Nucleons

Answer:

1. Atomic number: It is the number of protons present in the nucleus of an atom of the element.
2. Mass number: It is the sum of number of protons and neutrons present in the nucleus of an atom of the elements.
3. Atom: It is the smallest unit of matter which takes part in chemical reactions and it may or may not exist independently.
4. Ion: It is an atom or group of atoms having charge positive or negative and can exist freely in solution.
5. Element: It is a pure substance which can neither be built up nor broken into two or more still simpler substance by any physical or chemical method and it consists of only one kind of atoms.
6. Orbit: It is the fixed circular path traced by an electron revolving around the
7. Nucleons: The protons and neutrons present in the nucleus of an atom of the element are collectively known as nucleons.u

Short Answer Type Questions:

Question 1.
What do you understand by the structure of atom?
Answer:
According to the Dalton’s atomic theory, the smallest particle of matter is called atom. But later studies have shown that an atom is further made up of sub-atomic particles called electrons, protons and neutrons. Different atoms have different number of such particles and they also differ in the arrangement of these particles. Therefore, the atoms have different properties.

Question 2.
What happens when electric field is applied to the path of cathode rays? What does it show?
Answer:
When electric field is applied to the path of the cathode rays, these are deflected towards the positive plate of the field. This shows that the cathode rays consist of negatively charged particles.

Question 3.
What is the information conveyed by the following observations :

1. Atom is electrically neutral,
2. Mass of the atom is due to the nucleus.

Answer:

1. If an atom is electrically neutral, this means that it will have equal number of protons and electrons. Both protons and electrons have 1 unit charge but with opposite sign.
2. This means that nucleus contains in it both protons and neutrons which have mass.

Question 4.
What is the significance of number of protons found in the atoms in each of the different elements?
Answer:
The number of electrons in atom of the element is equal to the number of protons. By knowing no. of protons, we can calculate no. of electrons and hence its properties.

Question 5.
Write the electronic configuration of the elements A, B, C, D, E with atomic numbers 5, 6, 14, 13 and 15. Which have similar chemical properties?
Answer:

Element	Atomic No. (Z)	Electronic configuration
		K	L	M
A	5	2	3
B	6	2	4
C	14	2	8	4
D	13	?	8	3
E	15	2	8	5

Elements B and C. have similar chemical properties because both of them have 4 valence elt, trons.
Elements A and D have similar chemical properties because both of them have 3 valence electrons.

Question 6.
Five species P, Q, R, S, T have electrons, protons and neutrons are as follows:

Species	Electrons	Protons	Neutrons
P	4	3	4
Q	8	9	9
R	17	17	20
S	17	17	18
T	18	18	22

Find

1. a cation
2. an anion
3. a noble gas and
4. a pair of isotopes.

Answer:

1. Cation – Q
2. Anion – P
3. A noble gas = T
4. Pair of isotopes = R and S (because they have same number of electrons and protons but different number of neutrons).

Question 7.
Helium has only 2 electrons in the K-shell. But it is called an inert gas element. Why?
Answer:
Helium (He) atom has only one shell (K-shell) which can have a maximum of 2 electrons only. It cannot have more than 2 electrons. As a result, the combining capacity of He is zero. Therefore, its valency is also zero.

Question 8.
Give labelled diagram to show how are cathode rays produced?
Answer:

Question 9.
An atom has mass number A and atomic number Z.
1. How many protons are present in the nucleus?
2. How many electrons are revolving around the nucleus?
3. How many neutrons are present in its nucleus?
Answer:
Mass number = A
Atomic number = Z
1. No. of protons present in the nucleus = Z
2. No. of electrons revolving around the nucleus = Z
3. No. of neutrons present in the nucleus = A – Z.

Question 10.
State three ways by which a proton differs from an electron.
Answer:

Proton	Electron
1. It has one unit of positive charge. 2. It has mass 1.6 x 10-24 g. 3. It is present in the nucleus of an atom.	It has one unit of negative charge. It has mass 9.1 x 10″28 g. It is present in the extranuclear part of an atom.

Question 11.
What are isotopes? Give two uses of isotopes. Name the isotopes of hydrogen. Give their structures.
Answer:
Isotopes. The atoms of the same element having the same atomic number but different mass numbers are called isotopes.
Use of isotopes:
1. Isotopes of hydrogen, oxygen, carbon are used to study the mechanisms of organic reactions.
2. Some radioactive isotopes are used for the treatment of cancer and other diseases. The isotopes of hydrogen are:

Question 12.
Explain why elements have fractional atomic masses?
Answer:
The elements have fractional atomic masses due to the existence of isotopes (having different mass numbers) e.g. chlorine has two isotopes \({ }_{17}^{35} \mathrm{Cl}\) and \({ }_{17}^{37} \mathrm{Cl}\) and are present in the ratio 3:1.
∴ Average atomic mass of chlorine = \(\frac{35 \times 3+37 \times 1}{4}=\frac{105+37}{4} \) = 35.5 a.m.u.

Question 13.
What are isobars? Give examples.
Answer:
The atom of different elements having same mass numbers but different atomic numbers are called isobars.
e.g. 1. \({ }_{18}^{40} \mathrm{Ar}\) and \({ }_{19}^{40} \mathrm{Ar}\)
2. \({ }_{36}^{86} \mathrm{Ar}\) and \({ }_{38}^{86} \mathrm{Ar}\)

Question 14.
Sulphur has an atomic number 16 and a mass of 32. State the number of protons and neutrons in the nucleus of sulphur. Give a simple diagram to show the arrangement of electrons in an atom of sulphur.
Answer:

Atomic number of S = 16
Mass number of S = 32
∴ No. of protons = 16
No. of neutrons = 32 – 16 = 16
No. of electrons = 16

Question 15.
Write down the electronic configuration of the following:
1. \({ }_{13}^{27} \mathrm{X}\)
2. \({ }_{17}^{35} \mathrm{X}\)
Write down the number of electrons in X and neutrons in Y and the formula of
compound formed by X and Y.
Answer:
1. \({ }_{13}^{27} \mathrm{X}\)
Atomic number of X = 13
Mass number of X =27
No. of protons in X = 13
∴ No. of electrons in X = 13
The electronic configuration of X = 2, 8, 3
Valency of X = 3

2. \({ }_{17}^{35} \mathrm{X}\)
Atomic number of Y = 17
Mass number of Y =35
No. of protons in Y = 17
No. of electrons in Y = 17
No. of neutrons in Y = 35 – 17 = 18
The electronic co0nfiguration of Y = 2, 8, 7
Valency of Y = 1
The formula of the compound formed by X and Y

Question 16.
Give the important properties or characteristics of isotopes.
Answer:

1. The isotopes of an element have same atomic number (Z) i.e. the same number of electrons and same number of protons. Hence, they have identical chemical properties.
2. Isotopes of an element have same number of valence electrons and hence same valency.
3. Isotopes of an element have different mass numbers (or different number of neutrons) and hence they have different physical properties such as mass, density, melting point, boiling point etc.

Question 17.
An atom of the element is represented as 11x?

1. What does the numeral 23 indicate?
2. What does the nemeral 11 indicate?
3. What is the number of protons in X?

Answer:

1. 23 indicates mass number of X.
2. 11 indicates atomic number of X.
3. No. of protons in X = Atomic number = 11.

Question 18.
The atom of an element is made up of 4 protons, 5 neutrons and 4 electrons. what are its atomic number and mass number?
Answer:
No. of proton = 4
Atomic number of the element, Z = 4
No. of neutrons = 5
∴ No. of protons + No. of neutrons =4 + 5 = 9
∴ Mass number of the element, A = 9.

Question 19.
Calculate the number of neutrons in the following elements:
1. \({ }_{1}^{3} \mathrm{Cl}\)
2. \({ }_{17}^{37} \mathrm{Cl}\)
3. \({ }_{20}^{40} \mathrm{Cl}\)
Answer:
1. \({ }_{1}^{3} \mathrm{Cl}\)
Mass number = 3
Atomic number = 1
No.of neutrons = Mass no – Atomic no.
= 3 – 1 = 2

2. \({ }_{17}^{37} \mathrm{Cl}\)
Mass number = 37
Atomic number = 17
No.of neutrons = 37 – 17 = 20

3. \({ }_{20}^{40} \mathrm{Cl}\)
Mass number = 40
Atomic number = 20
No.of neutrons = 40 – 20 = 20

Question 20.
Give two conditions under which cathode rays are produced.
Answer:
Cathode rays are produced when a gas is subjected to the action of
1. High voltage of the order of 5000-10000 V and
2. Under a low pressure of the order of 10^-3 atm of Hg.

Question 21.
The electronic configuration of P (Z = 15) is 2, 8, 5. Why is the valency of phosphorus 3 and not 5?
Answer:
The electronic configuration of phosphorus (P) shows that it has 5 valence electrons. Its valency is expected to be 5. But it is not possible for the atom to lose 5 electrons present in the valence shell because the energy required to remove these electrons will be very high. Therefore, phosphorus atom has valency equal to 3 because to gain 3 electrons is easier than losing 5 electrons as it requires less energy.

Question 22.
What information is conveyed by the statement that the mass number of magnesium is 24 and the atomic number is 12?
Answer:
The atomic number (12) of magnesium indicates that its atom has 12 protons in the nucleus and an equal number of electrons in the extra nuclear portion. The mass number (24) points out that there are also 12 neutrons (24 – 12 = 12) present in the nucleus alongwith protons.

Question 23.
Is it possible for an atom to have 12 protons and 13 electrons? Explain.
Answer:
No, it is not possible. An atom must always be electrically neutral. This means that it has no net charge present on it. Now, each proton has one unit positive charge and each electron has one unit negative charge. In a neutral atom, the number of electrons and protons must always be the same. Thus, an atom cannot have 12 protons and 13 electrons.

Question 24.
Give the important isotopes of hydrogen, carbon, oxygen and chlorine. Indicate their mass numbers and atomic numbers.
Answer:

Numerical Problems (Solved):

Question 1.
Chlorine has two isotopes \({ }_{17}^{35} \mathrm{Cl}\) and \({ }_{17}^{37} \mathrm{Cl}\) in the ratio 3 : 1. Calculate the average atomic mass of chlorine.
Solution:

Question 2.
Out of ₁₈X and ₁₆Y which atom is chemically more reactive?
Solution:

No. of valence electrons in X =8
No. of valence electrons in Y =6
∴ Y is more reactive.

Question 3.
An element has 12 neutrons and mass number 23. Give the atomic number and symbol of the element.
Solution:

• Mass number(A) = 23
• Number of neutrons = 12
• Number of protons = 23 – 12 = 11
• Atomic Number(Z)= 11
• Symbol of the element = \(\frac{23}{11} \mathrm{Na}\)

Question 4.
Calculate number of protons, neutrons and electrons in \(\frac{235}{92} \mathrm{U}\) and \(\frac{238}{92} \mathrm{U}\). How are these atoms related?
Solution:
table
\(\frac{235}{92} \mathrm{U}\) and \(\frac{238}{92} \mathrm{U}\) are isotopes.

Question 5.
Calculate the number of electrons, protons and neutrons is \(\frac{19}{9} \mathrm{U}\). Also calculate its valency.
Solution:

1. Atomic number = 9
2. Mass number = 19
3. No. of protons = 9
4. No. of neutrons = 19 – 9 = 10
5. Electronic configuration = 2 7
6. Valency = 8 – 7 = 1.

Very Short Answer Type Questions

Question 1.
Who discovered canal rays?
Answer:
Goldstein discovered canal rays in 1886.

Question 2.
Which charge is present on canal ray particles?
Answer:
They carry positive charge.

Question 3.
Which charge is present on protons?
Answer:
Positive charge.

Question 4.
Where are protons present in an atom?
Answer:
Protons are present in the nucleus, deep inside the atom.

Question 5.
What were the characteristics of an atom according to Dalton?
Answer:
According to Dalton an atom was indivisible and indestructible.

Question 6.
Which discovery is against Dalton’s theory?
Answer:
Discovering of electrons and protons in an atom.

Question 7.
Who proposed the first model for the structure of atom?
Answer:
J.J. Thomson.

Question 8.
Why did Rutherford used gold foil in a-ray scattering experiment?
Answer:
This is because he wanted as thin a layer as possible. It was about 1000 atoms thick.

Question 9.
What are α-particles?
Answer:
They are doubly charged helium ions (He²⁺).

Question 10.
What is the charge on α-particles?
Answer:
+2 units.

Question 11.
What is the mass of an α-particle?
Answer:
4 u.

Question 12.
How the defects of Rutherford’s model were removed by Neil Bohr?
Answer:
The electrons revolve around the nucleus in an atom in fixed circular paths called orbits or energy levels and don’t lose energy.

Question 13.
What are energy levels or shells?
Answer:
The definite orbits in where electrons revolve around the nucleus are called energy levels. These are designated as K, L, M, N ……………. 1, 2, 3, 4.

Question 14.
Define mass number of an element.
Answer:
It is the sum of number of neutrons and protons present in the nucleus of the atom of the element.

Question 15.
Who gave the distribution of electrons in the various shells of an atom?
Answer:
Bohr and Bury.

Question 16.
What is the maximum number of electrons present in an electronic shell?
Answer:
2n² (Where n is the number of shells).

Question 17.
What is the maximum first four shells of an atom?
Answer:
2, 8, 18, 32.

Question 18.
What is the maximum number of electrons in the outermost shell of an atom?
Answer:
8

Question 19.
Which elements are chemically inert?
Answer:
These are the elements which have 8 electrons in their outermost shells.

Question 20.
Define octet.
Answer:
The maximum number of electrons present in the outermost shell of an atom is called octet.

Question 21.
Define valency of an element.
Answer:
It is the combining capacity of an atom of the element and it is equal to the number of electrons lost or gained or contributed for sharing from its valence shell in order to complete its octet.

Question 22.
Define atomic number.
Answer:
It-is the number of protons present in the nucleus of an atom of the element.

Question 23.
Define nucleon.
Answer:
The neutrons and protons present in the nucleus of an atom of the element are collectively known as nucleons.

Question 24.
Where is most of the mass of the element present?
Answer:
In the nucleus of an atom.

Question 25.
Define atomic mass of an element.
Answer:
It is the sum of the number of neutrons and protons present in the nucleus of its atom.

Question 26.
What are isotopes?
Answer:
Atoms of the same element having same atomic number but different mass numbers are called isotopes.

Question 27.
Write two isotopes of chlorine.
Answer:
\({ }_{17}^{35} \mathrm{Cl}\) and \({ }_{17}^{37} \mathrm{Cl}\).

Question 28.
Write two isotopes of carbon.
Answer:
\({ }_{6}^{12} \mathrm{Cl}\) and \({ }_{6}^{14} \mathrm{Cl}\).

Question 29.
Isotope of which element is used in the treatment of cancer?
Answer:
Isotope of cobalt (\({ }_{27}^{59} \mathrm{Co}\)).

Question 30.
What is the atomic mass of chlorine?
Answer:
35.5

Question 31.
Isotope of which element is used for the treatment of goitre?
Answer:
An isotope of iodine.

Question 32.
Isotope of which element is used in atomic reactor?
Answer:
Uranium.

Question 33.
What are isobars?
Answer:
Atoms of the different elements having same mass number but different atomic numbers are called isobars.

Question 34.
Give one example of isobars?
Answer:
\(\underset{(\text { Calcium })}{\stackrel{40}{20} \mathrm{Ca}}\) and \(\underset{(\text { Argon })}{\stackrel{40}{18} \mathrm{Ca}}\).

Question 35.
Write three isotopes of hydrogen.
Answer:

1. Protium (\({ }_{1}^{1} \mathrm{H}\))
2. Deuterium (\({ }_{2}^{1} \mathrm{H}\))
3. Tritium (\({ }_{3}^{1} \mathrm{H}\)).

Question 36.
What is the total number of electrons in an atom if its K-and L-shells are fully filled?
Answer:
10 (K-2, L-8).

Question 37.
What electrons in an atom influence its chemical properties?
Answer:
Valence electrons (electrons in the outermost shell).

Question 38.
How will you represent chlorine atom having mass number 35 and atomic number 17?
Answer:
\({ }_{17}^{35} \mathrm{Cl}\)

Question 39.
Name the sub-atomic particle on which size of an atom depends?
Answer:
Electron.

Question 40.
Name the atoms having same atomic number but different mass numbers.
Answer:
Isotopes.

Question 41.
Mg²⁺ has 10 electrons, what is the number of protons in it?
Answer:
10 + 2 = 12.

Question 42.
Name the element which has no neutrons in the nucleus of its atom.
Answer:
Hydrogen.

Question 43.
Out of electrons, protons and neutrons, which are same in isotopes?
Answer:
Electrons and protons.

Question 44.
There are three isotopes of hydrogen, \({ }_{1}^{1} \mathrm{H},{ }_{1}^{2} \mathrm{H},{ }_{1}^{3} \mathrm{H}\) all are electrically neutral, why?
Answer:
This is because each isotope has one electron and one proton.

Question 45.
An element has atomic number 16. Give its electronic configuration and number of valence electrons.
Answer:
Electronic configuration 2, 8, 6.

Question 46.
The number of electrons in the valence shell of sodium (Na) is ……………… .
Answer:
1.

Question 47.
Fluorine belongs to …………… family.
Answer:
Halogen.

Question 48.
In an atom, the number of …………… is the same as the number of ………………. .
Answer:
Electrons, protons

Question 49.
Sodium has …………….. electron …………….. than sodium ion.
Answer:
One, more

Question 50.
Isotopes of an element are …………….. because they have ……….. number of electrons.
Answer:
Chemically similar, same

Question 51.
The number of electrons in the valence shell of an atom cannot be ………………..>
Answer:
More than eight.

Punjab State Board PSEB 9th Class Science Important Questions Chapter 3 Atoms and Molecules Important Questions and Answers.

PSEB 9th Class Science Important Questions Chapter 3 Atoms and Molecules

Long Answer Type Questions:

Question 1.
(a) Write the important postulates of the Dalton’s Atomic Theory.
(b) Give four drawbacks of Dalton’s Atomic Theory.
Answer:
(a) Dalton’s atomic theory was given by John Dalton in 1808 to e×plain the nature of an atom and the chemical combination in the atoms. The main points of the theory are:

1. All matter is made up of a large number of e×tremely small particles called atoms.
2. An atom cannot be further divided.
3. Atoms are of different kinds. There are as many kinds of atoms as are of elements.
4. Atoms of a particular element are identical in all respects i.e. they have same mass and similar properties.
5. Atoms of the different elements are different i.e. they have different masses and properties.
6. Two or more atoms of the same or different elements combine to form compound atoms or molecules of compounds.
7. The number and the nature of atoms in a molecule always remains the same.
8. Atoms of the different elements combine in a simple whole number but fi×ed ratios to form compound atoms (now called molecules).
9. Atoms of the same element can combine to form two or more compounds.
10. Atom can neither be created nor be destroyed.

(b) Drawbacks of Dalton’s Atomic Theory:

1. Atom is no longer indivisible.
2. Atoms of the same element may not be always identical.
3. Atoms of different elements may have same atomic masses.
4. It does not e×plain the cause of chemical combination.

Question 2.
How to write a chemical formula of an ionic compound from its radicals?
Answer:
While writing the formula of an ionic compound, the following steps are used :

1. Write down the symbol or formula of positive ion to the left and the symbol or formula of the negative ion to the right.
2. Shift the valency of positive ion to the lower right of the negative ion and the valency of negative ion to the lower right of the positive ion.
3. Take out the common factor if any.
4. The formula compound radical is enclosed in small brackets and subscript is put outside the bracket. The subscript 1 is omitted.

Example

Question 3.
How will you write the name of a binary molecular compound?
Answer:
A covalent compound made up of two elements is called a binary molecular compound, e.g. water (H₂0).
While writing the name of a binary molecular compound, first write the name of the element whose symbol appears on the left hand side in the molecular formula and write down the name of other element. The name of the other element should end with ‘ide’. The prefi×es di, tri, tetra, penta etc. are used to indicate 2, 3, 4, 5…. atoms of an element.

Some examples are:

• Compound – Name
• CO – Carbon mono×ide
• CO₂ – Carbon dio×ide
• ZnO – Zinc O×ide
• SO₂ – Sulphur dio×ide
• PCl₃ – Phosphorus trichloride
• PCl₅ – Phosphorus pentachloride

Question 4.
Give one experiment to prove the truth of law of conservation of mass.
Answer:
1. Prepare 5% solution of barium chloride and sodium sulphate in separate beaker.
2. Take a small amount of solution of barium chloride in a conical flask and a small amount of solution of sodium sulphate in an ignition tube.

3. Suspend the ignition tube carefully in the conical flask with a thread and cork it.
4. Weigh the flask carefully. To prove the law of conservation of mass
5. Tilt and swirl the flask such that the two solutions get mi×ed and react.
6. Cool the flask to room temperature and again weigh it. The weight remains unchanged showing the truth of the law.

Short Answer Type Questions

Question 1.
Differentiate between an atom and a molecule.
Answer:

Atom	Molecule
1. It is the smallest particle of an element which takes part in chemical reactions. It may or may not exist freely.	1. It is the smallest particle of a substance which can exist freely.
2. Generally it is highly reactive.	2. It is less reactive.
3. It is less stable.	3. It is more stable.
4. It can’t be sub-divided.	4. It can be sub-divided.

Question 2.
(a) What do you understand by the term chemical formula?
(b) What qualitative information is given by the formula NH₃?
Answer:
(a) Chemical formula. The symbolic representation of a molecule of a substance is called its chemical formula. It indicates the actual number of atoms of various elements present in one molecule of a substance.
(b) NH₃ represents ammonia.

Question 3.
Write down the formulae of:
(a) Aluminium oxide
(b) Aluminium chloride
(c) Hydrogen sulphide
Answer:

Question 4.
Calculate the relative molecular masses of:
(a) Water (H₂O)
(b) Nitric Acid (HNO₃).
Answer:
(a) Molecular mass of water (H₂O) = 2 × 1 + 16 = 2 +16 = 18u.
(b) Molecular mass of nitric acid (HNO₃) = 1 + 14 + 3 × 16 =1 + 14 + 48 = 63u.

Question 5.
Write down the names of the compounds represented by the following formulae:

1. Na₂CO₃
2. MgCl₂
3. Al₂ (SO₄)₂
4. K₂ S0₄
5. NiS0₄
6. KN0₃
7. CaC0₃

Answer:

1. Sodium Carbonate
2. Magnesium Chloride
3. Aluminium Sulphate
4. Potassium Sulphate
5. Nickel Sulphate
6. Potassium Nitrate
7. Calcium Carbonate.

Question 6.
Work out the formula of:
1. Ammonia
2. Carbon dio×ide
3. Carbon tetrachloride.
Answer:

Question 7.
Calculate the number of moles in:
1. 52 g of He
2. 12.044 × 10₂₃ atoms of He
Answer:

Question 8.
Give one e×ample in each case;
(a) Diatomic molecule
(b) Triatomic molecule
(c) Monoatomic molecule
Answer:
(a) Dihydrogen (H₂)
(b) Ozone (0₃)
(c) Helium (He).

Question 9.
An element A has a charge of 3+. Write down the formulae of its:
(a) Chloride
(b) Sulphate
(c) Nitrate and
(d) Phosphate
Answer:

Question 10.
Write the formulae and names of the compounds between:
1. Sodium and sulphate ions
2. Aluminium and chloride ions
Answer:

Question 11.
Write the formulae of the compounds formed by:

1. Cr³⁺ and F^–
2. Pb²⁺ and \(\mathrm{SO}_{4}^{2-}\)
3. Mg²⁺ and S^2-
4. \(\mathrm{NH}_{4}^{+}\) and \(\mathrm{Cr₂O}_{7}^{2-}\)
5. K⁺ and \(\mathrm{CrO}_{4}^{2-}\)

Answer:

Question 12.
Calculate the formula mass of Na₂CO₃.10H₂O.
Answer:
Formula mass of Na₂,CO₃.10H₂O = 2 × 23 + 12 + 3 × 16 + 10 (2 × 1 + 16)
= 46 + 12 + 48 + 10 (2 + 16)
= 46 + 12 + 48 + 180
= 286 a.m.u.

Question 13.
(a) What do you understand by trivial names of compounds?
(b) Give the chemical names of five such compounds and give their trivial names.
Answer:
(a) The names of the compounds which do not follow any systematic rules are called trivial names or common names.
(b)

Compound	Chemical name	Trivial name
NH3	Nitrogen trihydride (AZANE)	Ammonia
NaCl	Sodium chloride	Common salt or Table salt
H2O	Hydrogen hydroxide (OXIDANE)	Water
NaOH	Sodium hydroxide	Caustic soda
PH3	Phosphorous trihydride (PHOSPHANE) .	Phosphine.

Question 14.
Calculate:
1. The number of atoms in 46 g of Na
2. No. of molecules in 8 g of O₂
Answer:

Question 15.
An element × shows two valencies i.e. 2 and 4. Write the formulae of its o×ides.
Answer:

∴ Formula of oxide – xO

Question 16.
Write the formulae of the following salts:

• Zinc carbonate
• Ammonium sulphate
• Barium chloride
• Sodium nitrate
• Lead hydro×ide
• Potassium permanganate

Answer:

• Name of the compound – Formula
• Zinc carbonate – ZnCO₃
• Ammonium sulphate – (NH₄)₂SO₄
• Barium chloride – BaCl₂
• Sodium nitrate – NaN0₃
• Lead hydro×ide – Pb(OH)₂
• Potassium permangante – KMnO₄

Question 17.
Write the names of the following compounds:

1. Al₂(S0₄)₃
2. Mg(HCO₃)₂
3. (NH₄)₂S
4. KMnO₄
5. KClO₃

Answer:
Formula of the Compound Name

1. Al₂(S0₄)₃ – Aluminium sulphate
2. Mg(HC0₃)₂ – Magnesium bicarbonate
3. (NH₄)₂ S – Ammonium sulphide
4. KMnO₄ – Potassium permanganate
5. KClO₃ – Potassium chlorate

Numerical Problems (Solved)

Question 1.
Weight of copper o×ide obtained by treating 2.16 g metallic copper with nitric acid and subsequent ignition was 2.70 g. In another e×periment, 1.15 g of copper o×ide on reduction yielded 0.92 g of copper. Show that these results illustrate the law of definite proportions.
Solution:
First experiment

• Weight of copper = 2.16 g
• Weight of copper o×ide = 2.70 g
• Percentage of copper in copper o×ide = \(\frac{2.16}{2.70}\) × 100 = 80
• Percentage of o×ygen in copper o×ide = 100

Second Experiment

• Weight of copper o×ide = 1.15 g
• Weight of copper = 0.92 g
• Percentage of copper in copper o×ide = \(\frac{0.92}{1.15}\) × 100 = 80
• Percentage of O in CuO = 100 – 80 = 20
• Since the percentage composition of copper o×ide in the two e×periments is the same. The above results illustrate the law of definite proportions.

Question 2.
Carbon and oxygen combine in the ratio 3 : 8 by mass to form carbon dio×ide. What mass of o×ygen would be required to react completely with 6 g of carbon?
Solution:
3 g of carbon gas reacts with o×ygen = 8 g
∴ 6g of carbon gas will react with o×ygen = 8/3 × 6 = 16 g

Question 3.
In water molecule the ratio by mass in which hydrogen and o×ygen react is 1 : 8. Calculate the ratio by number of atoms in water molecules.
Solution:

Element	Ratio by mass	Atomic mass	Relative no. of atoms	Simplest Atomic ratio
H	1	1	1/1 = 1	2
O	8	16	8/16 = 1/2 = 0.5	1

∴ Ratio by atoms in water molecule is H : O
2 : 1

Question 4.
Calculate the formula masses of the compounds whose formulae are given below:

1. MgO
2. CaCl₂
3. CaC0₃

Solution:
Formula mass of

1. MgO – 24 + 16 – 40 amu
2. CaCl₂ = 40 + 2 × 35.5 = 40 + 71 = 111 amu
3. CaC0₃ = 40 + 12 + 3 × 16 – 100 amu

Question 5.
What is the weight of 01 mole of HCl?
Solution:
Molecular weight of HCl = 1 + 35.5 = 36.5
Therefore, according to the mole-concept,
Weight of 1 mole of HCl = 36.5 g
∴ Weight of 0.1 mole of HCl = 36.5 × 01 g = 3.65 g

Question 6.
How many g of H₂O are present in 0.2 mole of it?
Solution:
Molecular weight of H₂O = 2 × 1 + 16 = 18
Therefore according to the mole-concept,
Number of grams present in 1 mole of H₂O = 18
∴ Number of grams present in 0-2 mole of H₂O = 0.2 × 18 = 3.6.

Question 7.
What is the mass of 0.1 mole of CO₂ in g?
Solution:
Molecular weight of CO₂ = 12 + 2 × 16 = 44
Therefore according to the mole concept
Mass of 1 mole of CO₂ = 44 g
∴ Mass of 0.1 mole of CO₂ = 44 × 0.1 g = 4.4 g

Question 8.
Calculate the number of moles of phosphorus atoms (P) in 100 g of phosphorus (Atomic mass of P = 31).
Solution:
The gram atomic mass of phosphorus (P) = 31 g
31 g of phosphorus atoms = 1 mole
100 g of phosphorus atoms = 100/31 =3.2 moles.

Question 9.
How many grams of o×ygen gas contain the same number of molecules as are present in 16 grams of sulphur dioxide? (Atomic masses : S = 32, O = 16).
Solution:
Gram molecular mass of sulphur dio×ide (S0₂) = 32 + 2 × 16 = 64 g
64 g of S0₂ contains = 6.022 × 10₂₃molecules
∴ 16 g of S0₂ contains = \(\frac{6.022 × 10₂₃}{64}\) × 16 = 1.5 × 10₂₃ molecules
Gram molecular mass of o×ygen (O₂) = 32 g
Gram Molecular mass of O₂ contain = 6.022 × 10₂₃molecules
Now 6.022 × 10₂₃ molecules of O₂ = 32 g
∴ 1.5 × 10₂₃ molecules of O₂ = \(\frac{32 × 1.5 × 10₂₃}{6.022 × 10₂₃}\) = 7.97 g

Question 10.
What is the mass in grams of each of the following:
(a) 1.0 mole of Ag
(b) 0.5 mole of Mg
(c) 6.023 × 10₂₃ atoms of P?
(Atomic mass : Ag = 108, Mg = 24, P = 31).
Solution:
(a) Atomic mass of Ag = 108
Gram atomic mass of Ag = 108 g
Gram atomic mass of Ag is the mass of 1.0 mole of Ag atoms.
∴ Mass of 1.0 mole of Ag atoms in grams = 108 g

(b) Atomic mass of Mg = 24
Gram atomic mass of Mg = 24 g
Gram atomic mass of Mg is the mass of 1.0 mole of Mg atoms
∴ Mass of 1 mole of Mg atoms in grams = 24 g
Mass of 0.5 mole of Mg atoms in grams = 24 × 0.5 = 12 g

(c) Atomic mass of P = 31
Gram atomic mass of P = 31 g
Gram atomic mass of P contains 6.023 × 10₂₃ atoms of P
6.023 × 10₂₃ atoms of P weigh = 31 g.

Question 11.
Calculate the number of o×ygen atoms in 010 mole of Na₂CO₃ . 10H₂O.
Solution:
Number of oxygen atoms in one molecule of Na₂CO₃.10H₂O
= 3 + 10 = 13
∴ Number of oxygen atoms in 1 mole of Na₂CO₃.10H₂O
= 13 moles
= 12 × 6.022 × 10²³
= 78.286 × 10²³
= 7.8 × 10²⁴

Question 12.
Calculate the actual weight of:
(a) an atom of oxygen
(b) a molecule of NH₃.
Solution:
(a) Atomic weight of oxygen = 16
∴ 1 gram atom of oxygen = 16 g
According to the mole concept,
Number of atoms in 16 g of oxygen = 6.023 × 10²³
i.e. Actual weight of 6.022 × 10²³ atoms of oxygen = 16 g
∴ Actual weight of 1 atom of oxygen = \(\frac{16}{6.022 × 10²³}\) g
= 2.651 × 10²³ g

(b) Molecular weight of ammonia (NH₃) = 14 + 3 × 1 = 17
∴ 1 mole of ammonia = 17 g

Question 13.
Find the number of molecules in 1.8 g of H₂O.
Solution:
Molecular weight of H₂O = 2 × 1 + 16 = 18
∴ According to mole-concept,
Number of molecules in 18 g of H₂O = 6.022 × 10₂₃
= 6.022 × 10²³
∴ Number of molecules in 1.8 g of H₂O =
\(\frac{6.022 × 10²³}{18}\) × 18
= 6.022 × 10²²

Question 14.
Which of the following would weigh most?
(a) 1 Mole of H₂O
(b) 1 Mole of CO₂
(c) 1 Mole of NH₃
(d) 1 Mole of CO
Answer:
1 Mole of H₂O = (2 × 1 + 16) g = 18 g
1 Mole of CO₂ = (12 + 2 × 16) g = 44 g
1 Mole of NH₃ = (14 + 3 × 1) g = 17 g
1 Mole of CO = (12 + 16) g = 28 g
∴ 1 Mole of CO₂ weighs most.

Question 15.
Calculate the number of moles of phosphorus atoms in 100 g of phosphorus. If phosphorus is considered to contain P4 molecules, then how many moles it has?
Solution:
Atomic mass of phosphorus = 31
∴ According to mole-concept,
Number of moles of phosphorus in 31 g = 1
Number of moles of phosphorus in 100g = 1/31 × 100 = 3.22
If phosphorus is considered to contain P₄ molecules, then according to mole-concept, Number of moles in 4 × 31 i.e. 124 g = 1
∴ Number of moles in 100 g = 1/124 × 100 = 0.805

Question 16.
Find the number of hydrogen atoms in 0.1 mole of H₂SO₄.
Solution:
Number of hydrogen atoms in 1 mole of H₂SO₄ = 2 × 6.022 × 10₂₃
Number of hydrogen atoms in 0-1 mole of H₂SO₄ = 0.1 × 2 × 6.022 × 10₂₃
= 1.2044 × 10₂₃ = 1.2 × 10₂₃

Question 17.
Calculate the number of atoms in each of the following:
(a) 52 moles of He
(b) 52 amu of He
(c) 52 g of He
Solution:

Very Short Answer Type Questions:

Question 1.
When did Indian philosophers thought of division of matter?
Answer:
Around 500 B.C.

Question 2.
What was the view of Maharishi Kanad regarding the division of matter?
Answer:
The smallest particle of matter will be indivisible.

Question 3.
What was the name of smallest indivisible particle by Kanad?
Answer:
Atom.

Question 4.
Which two Greek philosophers considered smallest particle as indivisible?
Answer:
Democritus and Leucippus.

Question 5.
What is the ratio by mass of H and O in water?
Answer:
1 : 8.

Question 6.
What is the ratio by mass of N and H in NH3?
Answer:
14 : 3,

Question 7.
What is Prout’s law of constant composition?
Answer:
A pure chemical compound is always made up of same elements combined together in the same fixed ratio by mass.

Question 8.
Who gave Atomic theory?
Answer:
John Dalton.

Question 9.
When did John Dalton gave atomic theory?
Answer:
In 1808.

Question 10.
What are the units used to e×press the atomic radius?
Answer:
Nanometre (nm).

Question 11.
What is the relationship between m and nm?
Answer:
1 nm = 10-9m.

Question 12.
What is the building block of all matter?
Answer:
Atom.

Question 13.
Who was the first scientist which used symbols for elements?
Answer:
Dalton.

Question 14.
What was special about symbols of elements given by Berzelius?
Answer:
The symbols of elements were represented by one or two letters of the name of the element.

Question 15.
What were the units used for e×pressing atomic masses of elements initially?
Answer:
Initially 1 /16th of mass of an atom of naturally occuring oxygen (016-isotope) was taken as unit.

Question 16.
When was C¹² isotope universally accepted as standard reference for expressed atomic masses?
Answer:
In 1961.

Question 17.
Which unit is used now-a-days to e×press atomic masses?
Answer:
It is 1 /12th of mass of an atom of carbon (C¹² – isotope).

Question 18.
Name the smallest particle of an element or compound which can exist freely?
Answer:
Molecule.

Question 19.
What is obtained when the atoms of the same element combine?
Answer:
Molecule.

Question 20.
How many atoms are present in oxygen molecule.
Answer:
Two, hence, it is called diatomic molecule (O₂).

Question 21.
Give four examples of diatomic molecules.
Answer:
H₂, O₂, N₂ and Cl₂.

Question 22.
Give one example of tetra-atomic molecule.
Answer:
Phosphorous, (P₄).

Question 23.
Give one example sample of octa-atomic molecule.
Answer:
Sulphur, (S₈).

Question 24.
What is produced when three atoms of oxygen combine.
Answer:
Ozone (O₃).

Question 25.
Name isotopes of carbon.
Answer:
C¹², C¹³ and C^14.

Question 26.
What is the ratio by mass of C and O in carbon dioxide?
Answer:
3 : 8

Question 27.
What is the ratio by number between the atoms of H and O in water?
Answer:
2 : 1

Question 28.
Define an ion.
Answer:
It is an atom or group of atoms having charge (positive or negative).

Question 29.
What is a cation?
Answer:
It is an ion having positive charge.

Question 30.
What is an anion?
Answer:
It is an ion having negative charge.

Question 31.
What is the ratio by mass of Ca nd O in calcium oxide (CaO)?
Answer:
5 : 2

Question 32.
What is the ratio by mass of Mg and S in magnesium sulphate?
Answer:
3 : 4

Question 33.
What is the ratio by mass of Na and Cl in sodium chloride (NaCl)?
Answer:
23 : 35.5

Question 34.
Define chemical formula?
Answer:
It is the symbolic representation of a molecule of a substance.

Question 35.
Define valency.
Answer:
It is the combining capacity of an atom of the element.

Question 36.
What are diatomic molecules?
Answer:
These are made up of two atoms made up of same or different elements.

Question 37.
Define molecular mass of a subtance?
Answer:
It is the average relative mass of one molecule of substance as compared to the mass of one atom of carbon, (C¹²-isotope).

Question 38.
Which unit is used for expressing molecular masses?
Answer:
a.m.u.

Question 39.
What is the new name given to a.m.u. by IUPAC?
Answer:
U (Unified).

Question 40.
Name the elements present in water (H₂O).
Answer:
Hydrogen and oxygen.

Question 41.
What is one mole of an element?
Answer:
It is the number of an element whose mass in grams is numerically equal to its atomic mass e×pressed in a.m.u. or 1 gram atom of an element represents one mole.

Question 42.
What is Avogardro’s number?
Answer:
Avogardro’s number contains 6.022 × 10²³ particles.

Question 43.
How is Avogadro’s number denoted?
Answer:
By No or NA.

Question 44.
In what ratio elements combine to form a compound?
Answer:
In a fixed ratio by mass.

Question 45.
Which scientist gave law of conservation of mass?
Answer:
Russian scientist Lavoisier in 1756.

Question 46.
Which scientist gave law of constant composition?
Answer:
French scientist Joseph L. Proust in 1799.

Question 47.
What does a.m.u. represent?
Answer:
It is the unit used to express atomic masses.

Question 48.
Which isotope of carbon is used as a standard reference to express atomic masses?
Answer:
C¹² – isotope.

Question 49.
Most of the elements have fractional atomic masses, what does it show?
Answer:
This indicates the existence of isotopes of an element.

Question 50.
What is molar mass?
Answer:
It is the mass of 1 mole of a substance in grams.

Question 51.
Define gram atomic mass.
Answer:
It is the mass of 1 mole of atoms (6.022 × 10²³) in grams.

Question 52.
How many atoms are present in 1 gram atom of an element?
Answer:
6.022 × 10²³.

Question 53.
Do 1 mole of sodium and calcium have different number of atoms?
Answer:
No, they have same number of atoms.

Question 54.
Lead nitrate solution and sodium chloride solution taken in separate beakers. The beakers were weighed and mixed in one beaker and the beaker was weighed again. Does weight remains unchanged or not? On what principle, the answer is based upon?
Answer:
The weight remains unchanged. It is based upon law of conservation of mass.

Question 55.
28 g of magnesium oxide is produced by the combination of 12 g of magnesium and 16 g of oxygen. Which law is illustrated by this data?
Answer:
Law of conservation of mass.

Question 56.
Do 1 mole of Na and 02 have same mass?
Answer:
No, 1 mole of Na has mass = 23 g
1 mole of O₂ has mass = 32 g

Question 57.
1 mole represents particles …………. .
Answer:
6.022 × 10₂₃.

Question 58.
The molar mass of NH3 is
Answer:
17 g.

Question 59.
An element Z has a valency of 3. Write down the formula of its oxide?
Answer:
Z₂O₃.

Question 60.
How many atoms are present in 0.012 kg of C¹² – isotope? What is this number called?
Answer:
6.022 × 10²³ atoms. This number is called Avogadro’s number.

Question 61.
Write down the formula of compound made up of Al³⁺ and [latetx]\mathrm{SO}_{4}^{2-}[/latex].
Answer:
Al₂ (SO₄)₃

Question 62.
How many molecules are present in 9 g of water?
Answer:
9/18 × 6.0222 × 10₂₃ = 3.011 × 10₂₃ molecules.

Question 63.
What is the molecular mass of HN03. (Atomic masses, H = lu, N = 14u, 0 = 16u)
Answer:
1 + 14 + 3 × 16 = 1 + 14 + 48 = 63u.

Question 64.
What are polyatomic ions?
Answer:
It is a group of atoms having net charge, e.g. NH⁺₄, CO₃^2- etc.

Question 65.
The molecular formula of aluminium sulphate is ……….. .
Answer:
Al₂(SO₄)₃

Punjab State Board PSEB 9th Class Science Important Questions Chapter 2 Is Matter Around Us Pure Important Questions and Answers.

PSEB 9th Class Science Important Questions Chapter 2 Is Matter Around Us Pure

Long Answer Type Questions:

Question 1.
(a) Define mixture. Give examples.
(b) What are the types of mixtures?
Answer:
(a) Mixture. It is a product obtained by mixing two or more substances (elements and / or compounds) in any proportion. For example,

1. Air is a mixutre of nitrogen, oxygen, carbon dioxide, water vapour etc.
2. Smoke is a mixture of carbon particles and air.
3. Gun Powder is a mixture of nitre, sulphur and charcoal.
4. Brass is a mixture of copper and zinc.

(b) Types of mixtures. Mixtures are of two types:
1. Homogeneous mixtures and
2. Heterogeneous mixtures.
1. Homogeneous mixtures: A mixture in which the different constitutents are mixed uniformly and has the uniform composition throughout is called homogeneous mixture, e.g. Brass is a homogeneous mixture of copper and zinc, an aqueous solution of sodium chloride is a homogeneous mixture of sodium chloride and water.
2. Heterogeneous mixtures: A mixture in which the different constitutents are not mixed uniformly is called heterogeneous mixture, e.g. soil is a heterogeneous mixture, a mixture of common salt, sand and sulphur is a heterogeneous mixture.

Question 2.
Give important characteristics of a mixture.
Answer:
The important characteristics of a mixure are:

1. In a mixture, the components, elements or compounds are present in no fixed ratio.
2. A mixture is formed from its components as a result of physical change.
3. The properties of a mixture lie between those of its constituents.
4. A mixture may be homogeneous or heterogeneous.
5. The constituents of a mixture can be separated by physical methods only.
6. The formation of a mixture from its constituents does not involve any energy change.

Question 3.
What are the various types of binary solutions based upon the physical states
of solute and solvent?
Answer:
These are of nine types:

Solute	Solvent	Type of solution	Example
1. Solid	Solid	Solution of solid in solid	Brass
2. Solid	Liquid	Solution of solid in liquid	Sugar in water
3. Solid	Gas	Solution of solid in gas	Iodine in air
4. Liquid	Solid	Solution of liquid in solid	CuS04. 5H20
5. Liquid	Liquid	Solution of liquid in liquid	Ethyl alcohol in water
6. Liquid	Gas	Solution of liquid in gas	Moisture in air
7. Gas	Solid	Solution of gas in solid	Hydrogen in palladium
8. Gas	Liquid	Solution of gas in liquid	Carbon dioxide dissolved in water
9. Gas	Gas	Solution of gas in gas	Air

Question 4.
State briefly how would you separate or name the process use to separate:

1. Common salt from a solution of common salt and water.
2. Alcohol from a mixture of alcohol and water.
3. Sulphur from a mixture of carbon particles and powdered roll sulphur.
4. The coloured dyes in black ink.

Answer:

1. The solution containing common salt in water is concentrated and is then cooled. The crystals of common salt are formed which can be separated by filtration.
2. Alcohol can be separated from water by fractional distillation as the two liquids differ much in their boiling points.
3. The mixture is treated with carbon disulphide which dissolves powdered sulphur in it. It is filtered to separate carbon particles. The filtrate upon concentration and cooling gives crystals of sulphur which can be separated by the process of filtration.
4. The coloured dyes in black ink can be separated by the process of paper chromatography.

Question 5.
Give important differences between a compound and a mixture.
Answer:

Compound

Mixture

1. A compound is formed from its constituent elements as a result of chemical reaction. 2. A compound is always homoge­neous in nature. 3. In a compound the elements are present in a fixed ratio by weight. 4. The components of a compound can’t be separated by physical methods but can be separated by chemical methods only. 5. The properties of a compound are different from that of its elements. 6. The formation of a compound from its elements is accompanied by energy changes.

1. A mixture is obtained from its (elements, compounds) components as a result of physical change. 2. The mixtures can be homogeneous or heterogeneous. 3. In a mixture the components can be present in any ratio. 4. The components of a mixture can be separated by physical methods only. 5. The properties of a mixture lie between those of its components. 6. The formation of a mixture from its constituents is not accompanied by energy changes.

Question 6.
How are mixtures classified on the basis of their physical states?
Answer:
On the basis of their physical states, the mixtures are of the following types

Constituents of mixture	Nature of mixture	Example
1. Solid-Solid mixture	Homogeneous	Brass
2. Solid-Solid mixture	Heterogeneous	Common salt and sand
3. Solid-Liquid mixture	Homogeneous	Sugar in water
4. Solid-Liquid mixture	Heterogeneous	Sulphur in water
5. Liquid-Liquid mixture	Homogeneous	Water and alcohol
6. Liquid mixture	Heterogeneous	Carbon tetrachloride and water
7. Liquid-gas mixture	Homogeneous	Carbon dioxide dissolved in water
8. Gas-Gas mixture	Heterogeneous	A mixture of Nitrogen and Oxygen

Question 7.
Explain the following:
(a) Fractional crystallisation
(b) Sublimation
(c) Filtration
Answer:
(a) Fractional Crystallisation. The process of separation of components of a mixture having different solubilities in the same solvent is called fractional crystallisation. This method is used for the separation of components of a mixture which are soluble in the same solvent on heating but have different solubilities.
For example, a mixture of potassium nitrate and sodium chloride can be separated by this method.

This can be explained as follows:
The mixture is dissolved in water. The solid is concentrated to the crystallisation point. On cooling the crystals of less slouble component i.e., sodium chloride appear first. These are separated. On further cooling the crystals of more soluble component i.e., of potassium nitrate will appear. The pure crystals can be obtained by recrystallisation from the same solvent i.e, water.

(b) Sublimation: This method is used for the separation of the components of a mixture in which one component undergoes sublimation whereas other does not. For example, a mixture of ammonium chloride and common salt can be separated by this purpose take the mixture of ammonium chloride and common salt in a china dish. Cover it with an inverted funnel and its open end is to be closed with cotton wool. The walls of china dish are kept booled. On heating, ammonium chloride sublimes and condenses on the cooler parts whereas common salt is left behind. The fine powder of ammonium chloride deposited on the funnel is scrapped with the help of a knife.

Similarly, the mixture of iodine and sand can be separated by this method in which iodine sublimes whereas sand does not.

(c) Filtration. In this method, the mixutre is dissolved in a suitable solvent in which one component dissolves whereas other does not.

For example, a mixture of charcoal and sulphur can be separated by this method. The mixture is treated with carbon disulphide which dissloves sulphur whereas charcoal is left behind. The insoluble charcoal is separated by filtration and is dried. From the filtrate, sulphur can be obtained by evaporating carbon disulphide.

Question 8.
Explain the process of:
1. Distillation
2. Evaporation
Answer:
1. Distillation: The process of converting a liquid into gaseous state by heating to boiling point and condensing the vapour to get the pure liquid is called distillation.
For example, salt can be separated from sea water by this method. For this purpose the apparatus is fitted as shown below:

The mixture of solid and liquid is taken in a distillation flask. On heating vapour of liquid (water) are produced. These are condensed in water condenser and collected in a receiver. The non-volatile sodium chloride is left behind. Similar, a mixture of methyl alcohol and iodine i an be separated by this method.

2. Evaporation: Evaporation is a process of changing a liquid into its gaseous state by heating it at a temperature below its boiling point. For example, common salt can be obtained from a mixture of common salt and water by evaporation.

The mixture is heated in a china dish using sand bath when water vaporises whereas common salt is left behind.

Question 9.
What is chromatography? Why is it regarded as superior method of purification?
Answer:

• Chromatography. The process of separation of different components of a mixture by adsorbing them over a suitable material (called adsorbent) is called chromatography.
• Originally, this technique was used to separate coloured mixtures but now-a-days this method can be used for colourless as well as coloured substances.

The main advantages of this technique are:

1. It can be applied to separate the mixture even if very small amount of mixture of the substances is available.
2. The components of a mixture don’t get wasted during separation.
3. It also helps in estimating the constituents of a mixture apart from separation.

Question 10.
What is the principle of chromatographic separation? Name the different types of chromatography commonly used.
Answer:
Chromatography is based upon the distribution of the mixture of the components between the two phases i.e. a stationary phase and a moving phase. The moving phase consists of mixture of the substances to be separated. The moving phase is applied over a solid or liquid i.e., a stationary phase. The stationary phase separates the components of the mixture by the phenomenon of either partition, adsorption or ion exchange. The different chromatographic techniques are:
(a) Column chromatography
(b) Thin layer chromatography
(c) Ion exchange chromatography
(d) Paper chromatography.

Question 11.
How will you separate gas-gas mixtures?
Answer:
The gas-gas mixtures can be separated by the following method:
Fractional evaporation of mixture of liquefied gases. The mixture of two gases is liquefied by applying high pressure and then allowing it to expand. For example, when air is liquefied under high pressure and allowed to stand, both oxygen and nitrogen get liquefied.

The above liquid mixture is maintained at a temperature of -196°C (b.pt. of liquid N₂), nitrogen boils off. For example, a mixture of carbon dioxide and hydrogen can be separated by passing through porous partitions as showm below.

In this case, H₂ being lighter diffuses at a faster rate as compared to CO₂.

Question 12.
What are the various types of colloidal solutions based upon the physical states of dispersed phase and dispersion medium? Give one example in each case.
Answer:
These are of eight types:

Dispersed Phase	Dispersion Medium	Type or name of colloidal solution	Examples
1. Solid	Solid	Solid sol	Some coloured glasses
2. Liquid	Solid	Gel	Cheese, butter
3. Gas	Solid	Solid foam	Sponge, rubber foam
4. Solid	Liquid	Sol	Mud, milk of magnesia
5. Liquid	Liquid	Emulsion	Milk, hair cream
6. Gas	Liquid	Foam	Froth, whipped cream
7. Solid	Gas	Solid aerosol	Smoke
8. Liquid	Gas	Liquid aerosol	Fog, mist

Question 13.
Define concentration of a solution. How is concentration of a solution expressed?
Answer:
Concentration of a solution. It indicates the amount of solute dissolved per unit mass or volume of solvent or solution.
The concentration of a solution can be expressed as

Question 14.
Describe how you would separate the constituents of the following mixtures in a reasonably pure state:
(a) Sand and iodine
(b) Water and sugar
(c) Ingredients of gun powder
(d) Sulphur, sand and common salt
(e) Carbon dioxide and carbon monoxide.
Answer:
(a) Sand and iodine. The mixture can be separated by sublimation when iodine sublimes whereas sand is left behind.

(b) Water and sugar. Sugar and water can be separated by evaporation when water evaporates and sugar is left behind.

(c) Ingredients of gun powder. Gun powder is a mixture of sulphur, nitre and charcoal. Shake the mixture with water. Nitre passes into solution separated by filtration. Evaporate the filtrate. We get pure nitre.
Shake the residue obtained above with carbon disulphide when sulphur dissolves while charcoal is separated by filtration. From filtration sulphur is obtained by evaporating carbon disulphide.

(d) Sulphur, sand and common salt. Shake the mixture with water and filter. Common salt passes into solution. The filtrate is evaporated to get common salt.
Shake the residue obtained above with carbon disulphide and filter sulphur goes into the filtrate. Evaporate it when sulphur is left behind. Sand is left behind insoluble in carbon disulphide.

(e) Carbon dioxide and carbon monoxide. The mixture can be separated by diffusion through a porous pot when carbon monoxide differ faster than carbon dioxide and thus get separated.

Question 15.
What is paper chromatography? How will you separate the coloured constituents present in a mixture of ink and water?
Answer:
The process of separation of different dissolved components of a mixture by adsorbing them on a suitable material (called adsorbent) is called chromatography. The adsorbent can be solid or liquid. For example, alumina, magnesium oxide, special filter paper.
The components of a mixture are generally dissolved in a solvent like water, alcohol etc. If a filter paper is used as an adsorbent for the separation of components of a mixture, this technique is called paper chromatography.

The process of separation of coloured constituents present in a mixture of ink and water is described ahead:
1. Take a special filter paper about 25 cm long and 4 cm broad and stick it to a glass rod at its one end with the help of gum as shown below. Mark a line at a distance of 3 cm from the lower end with the help of pencil. Put a drop of ink at the centre of this line with the help of a fine capillary.
2. Dip this end in water taken in a beaker upto 2 cm.
3. Suspend this filter paper in a tall cylinder and allow it to stand undisturbed for one hour. The water rises up the filter paper and reaches the ink drop, dissolves its components and rise upwards along with water. The different components of ink are adsorbed upto different extents on the filter paper, therefore, they travel different distances on the filter paper.
4. After one hour, the filter paper is taken out and dried. Different of colours corresponding to the components of ink are produced on the filter paper. This filter paper is called chromatograph.

Question 16.
Briefly describe simple methods of separating the following mixtures:
(a) Powdered chalk and sugar
(b) Nitre and common salt
(c) Iron and copper filings
(d) Ammonium chloride, sand and common salt
(e) Ammonia and hydrogen.
Answer:
(a) Powdered chalk and sugar can be separated by using water which dissolves sugar and chalk is insoluble. It is separated by filtration. From sugar solution, sugar is obtained by evaporating water.

(b) Nitre and common salt. The mixture can be separated by fractional crystallisation from the solutions in water because they have different solubilities in water.

(c) Iron and copper filings can be separated by using a magnet when iron filings cling to magnet whereas copper filings don’t.

(d) Ammonium chloride, sand and common salt. Ammonium chloride is separated by sublimation. Sand and common salt are separated by using water when sand remains insoluble and is separated by filtration, From aqueous solution, sodium chloride can be separated by evaporation.

(e) Ammonia and hydrogen can be separated by diffusion through porous pot. Ammonia and hydrogen have different rates of diffusion due to different densities.

Question 17.
How will you separate liquid-liquid mixture or immiscible liquids?
Answer:
The liquid-liquid mixtures can be separated by using :
1. Separating funnel.
2. Fractional distillation.
1. Separation of liquid-liquid mixture by using separating funnel. This method is used when the two liquids are immiscible. For example, a mixture of carbon disulphide and wrater can be separated by this method.

The mixture is taken in a separating funnel. The funnel is allowed to stand for sometime. On standing, the liquid having higher density forms the lower layer whereas the liquid having lower density forms the upper layer. The two liquids are taken out from the separating funnel in separate conical flask.

2. Separation of liquid-liquid mixture using fractional distillation:

The process of separating the mixture of two immiscible liquids by using distillation carried out with the help of a long fractionating column is called fractional distillation.
For example, a mixture of ethyl alcohol and water can be separated by this method. The apparatus is fitted as shown below:

The mixture of ethyl alcohol anci water is heated in a distillation flask fitted with a fractionating column. On heating the vapour of liquid having lower boiling point are produced first and condensed in the water condenser and collected in a receiver. When the temperature of thermometer begins to rise, the vapour of other liquid are produced and these are condensed and collected in a separate receiver.

Question 18.
How will you separate the solid-liquid mixtures?
Answer:
The solid-liquid mixtures can be separated by the following methods:
1. By sedimentation and decantation. In this method, the mixture is allowed to stand when the solid particles settle down as sediment whereas clear liquid is left behind which is poured out carefully. This process is called decantation e.g. mixture of sand and water can be separated by this method. By this method, the complete separation is not possible.

2. By filtration. In this method, the mixture can be separated by using filter paper when the insoluble solid is left on the filter paper whereas the clear liquid passes out from the filter paper and is collected. For example, a mixture of chalk and water can be separated by this method.

Short Answer Type Questions:

Question 1.
Give three characteristics of a pure substance.
Answer:

1. It is homogeneous.
2. It has a definite set of properties.
3. A pure substance cannot be separated into other kinds of matter by any known physical method.

Question 2.
Give three examples each of two classes of pure substances.
Answer:
Pure substances are of two types:
(a) Elements e.g. carbon, nitrogen, oxygen etc.
(b) Compounds e.g. ammonium, water, carbon dioxide etc.

Question 3.
Give three characteristics of a mixture.
Answer:
(a) The components of a mixture are present in any ratio.
(b) It can be homogeneous or heterogeneous.
(c) The mixture can be separated with its constituents by physical or mechanical methods only.

Question 4.
Name the methods commonly used for separation of components of a mixture.
Answer:
These are:

1. Evaporation
2. Crytallisation
3. Centrifugation
4. Using separating funnel
5. Simple distillation
6. Fractional distillation
7. Chromatography
8. Sublimation

Question 5.
Define colloidal solution.
Answer:
It is a heterogeneous mixture or solution in which the particles having size 1 to 100 11m are suspended in a suitable solvent or dispersion medium. For example, starch solution.

Question 6.
Define dispersed phase and dispersion medium.
Answer:

• Dispersed phase: In the colloidal solution colloidal particles constitute dispersed phase.
• Dispersion medium: In the colloidal solution the medium in which colloidal particles are dispersed in called dispersion medium.
• e.g. in the colloidal solution of starch in water, starch particles constitutes dispersed phase and water constitutes dispersion medium.

Question 7.
From the methods (or techniques) of distillation, filtration, fractional distillation, chromatography, crystallisation, select and write down the technique you would use to separate:

1. Constituents of colouring matter in ink.
2. Hydrated copper (II) sulphate or blue vitriol from its aqueous solution.
3. Nitrogen from liquid air.
4. Unused zinc after the reaction of excess of zinc with dilute sulphuric acid.

Answer:

1. Chromatography
2. Crystallisation
3. Fractional distillation
4. Filtration.

Question 8.
Name the technique which could be used to separate:
1. Iodine crystals from sand
2. Petrol from crude oil.
Answer:
1. Iodine crystals can be separated from sand by sublimation.
2. Petrol can be separated from crude oil by fractional distillation.

Question 9.
How will you separate:
1. Pure water from sea water?
2. Kerosene oil from a mixture of kerosene oil and petrol?
Answer:
1. It can be obtained by the process of distillation. When sea water is distilled, water distils, and vapour are condensed in a receiver whereas common salt is left behind in the retort.
2. Kerosene oil can be separated from a mixture of kerosene oil and petrol by fractional distillation when petrol distils off first and then kerosene oil distils off. .

Question 10.

1. Name the kind of change of state when naphthalene changes into gaseous state.
2. Name one element which undergoes similar change as in (i).
3. Name a common substance which exists in all the three states of matter.

Answer:

1. Sublimation
2. Ammonium chloride
3. Water.

Question 11.
Define electrophoresis.
Answer:
Electrophoresis is the process of migration of colloidal particles towards oppositely charged electrode under the influence of an electric field is called electrophoresis. The electrophoresis is due to the charge present on the colloidal particles.

Question 12.
Explain Brownian movement.
Answer:
Brownian movement. When colloidal solutions are viewed with the help of ultra-microscope, it is observed that colloidal particles follow zig-zig path. This is called brownian movement. This effect is due to the unequal impacts of the particles of dispersion medium with colloidal particles.

Question 13.
Explain Tyndall effect.
Answer:
Tyndall effect. If a bright, narrow and convergent beam of light is passed through a colloidal solution and is viewed at right angles with the help of a microscope, the path of light becomes visible and a bright cone of light called Tyndall cone is produced. This luminosity of path of a beam of light in a colloidal solution is called Tyndall effect.

Question 14.
Define physical change and chemical change.
Answer:

• Physical Change. It is a temporary change in which only the physical properties of substances change and it can be easily reversed.
• Examples: Glowing of an electric bulb, evaporation of water.
• Chemical Change: It is a permanent change in which the chemical properties of substances change and there is a change in composition and cannot be reversed.
• Examples: Baking of a cake, Drying of a paint etc.

Question 15.
Classify the following substances into elements, compounds and mixtures:

1. Cane sugar
2. Zinc
3. Oxygen
4. Marble
5. Bronze
6. Nitre
7. Air
8. Milk
9. Iron
10. Stainless steel

Answer:

1. Cane sugar – Compound
2. Zinc – Element
3. Oxygen – Element
4. Marble – Mixture
5. Bronze – Mixture
6. Nitre – Compound
7. Air – Mixture
8. Milk – Mixture
9. Iron – Element
10. Stainless steel – Mixture

Question 16.
1. Name the process used to separate the constituents liquefied air.
2. State how will you remove carbon dioxide from a mixture of carbon dioxide and carbon monoxide.
Answer:
1. Fractional evaporation.
2. Pass the mixture through potassium hydroxide solution. Carbon dioxide is absorbed by KOH solution.
2KOH + C0₂ → K₂C0₃ + H₂0
Carbon monoxide is left behind and is collected over water by downward displacement of water.

Question 17.
How would you separate:
(a) Benzene (b.pt. 80°C) from toluene, methylbenzene (b.pt. 111°C) with which it is miscible?
(b) Kerosene oil from a mixture of kerosene oil and petrol?
(c) Lead sulphate from a mixture of lead sulphate and lead chloride?
Answer:
(a) By using simple distillation when benzene distils off first and its vapours are condensed and collected in a receiver.

(b) Kerosene oil from a mixture of kerosene oil and petrol can be obtained by using separating funnel when kerosene oil forms upper layer.

(c) Lead sulphate from a mixture of lead sulphate and lead chloride can be obtained by boiling with water which dissolves lead chloride and insoluble lead sulphate is separated by filtration.

Question 18.
A molecule can be formed by an element as well as by a compound. Explain.
Answer:
A molecule is the smallest particle of a substance i.e. an element or a compound which can exist freely. It has all the properties of that substance, e.g. a molecule of hydrogen (H₂), a molecule of methane (CH₄).

Question 19.
Can a mixture of chloroform (b.pt. 61°C) and carbon tetrachloride (b.pt. 77°C) be satisfactorily separated by the process you use for separating the various fractions of petroleum?
Answer:
Yes, a mixture of chloroform and carbon tetrachloride can be separated by using fractional distillation as used for the separation of various fractions of petroleum. The heating should be carried out slowly on a sand bath and vapours are condensed in a Liebig condenser and collected in separate receivers.

Question 20.
Name a mixture used:

1. by all living beings
2. in the construction of buildings
3. as a food

Answer:

1. Air
2. Cement
3. Milk

Question 21.
Give two advantages of paper chromatography.
Answer:
1. It can be applied even to a very small amount of the mixture of the substances.
2. The components of a mixture don’t get wasted during separation.

Question 22.
How would you obtain a sample of sulphur from a mixture of sulphur and carbon?
Answer:
Shake the mixture of sulphur and carbon with carbon disulphide and filter. Sulphur will be present in the filtrate and the residue is carbon. The filtrate is evaporated when carbon disulphide vaporises while sulphur is left behind.

Question 23.
How would you obtain pure ammonium chloride when it contains potassium chloride as an impurity?
Answer:
The mixture is heated. Ammonium chloride sublimes and its vapour are condensed in an inverted funnel. Potassium chloride is left behind. From the funnel ammonium chloride is scrapped with a knife.

Question 24.
Name three metals which are liquids at room temperature.
Answer:
These are mercury, cesium and gallium.

Question 25.
Name the various noble gases.
Answer:
The various noble gases are: Helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe) and Radon (Rn).

Question 26.
Which of the following statements are correct and which are incorrect?

1. Milk is a mixture.
2. Smoke is a mixture of solids and gases.
3. Ice cream is a mixture.
4. Mercury is a solid
5. Thums up is a homogeneous mixture.

Answer:

1. True
2. True
3. True
4. False
5. True.

Question 27.
If you are given a mixture of hydrogen and carbon dioxide, how would you remove the carbon dioxide gas?
Answer:
The carbon dioxide gas can be removed by passing the gaseous mixture through potassium hydroxide solution which absorbs carbon dioxide and hydrogen gas is set free.

Question 28.
Give two pieces of evidence that sodium chloride is a compound.
Answer:
Sodium chloride is a compound because:
1. in sodium chloride, sodium and chlorine are combined chemically in a fixed ratio by mass.
2. the formation of sodium chloride from sodium and chlorine is accompanied by loss of energy.

Question 29.
Give reasons to show that ammonia is a compound.
Answer:

1. The properties of ammonia are different from those of its components i.e. nitrogen and hydrogen.
2. When ammonia is formed from nitrogen and hydrogen, energy is given out.
3. In ammonia, N and H are present in fixed ratio of 14 : 3 by mass.

Question 30.
Give three reasons why air is considered a mixture and not a compound.
Answer:
In air:

1. the components are not present in any fixed ratio.
2. the properties of air are average of the properties of its components.
3. the components can be separated by physical methods.

Question 31.
Define crystallisation. Give its importance.
Answer:
It is a process in which a pure solid in the form of crystals is separated by cooling its hot saturated solution in a suitable solvent.
Importance:
1. For the purification of salt obtained from sea water.
2. To get crystals of alum from impure samples.

Question 32.
1. Some reduced iron filings and powdered roll sulphur are well mixed and heated in a test tube. Describe all what you observe.
2. Name the grey mass which is formed in test tube at the end of reaction.
3. Would you call the above reaction: exothermic or endothermic?
Answer:
1. When iron filings and powdered roll sulphur are well mixed and heated in a test tube, iron (II) sulphide is produced

2. Grey mass of iron (II) sulphide is produced.
3. The above reaction is endothermic, because heat energy is absorbed.

Question 33.
What are exothermic and endothermic reactions?
Answer:
1. Exothermic reaction: It is a chemical reaction in which heat energy is evolved. e.g. burning of candle.
2. Endothermic reaction: It is a chemical reaction in which heat energy is absorbed e.g. decomposition of calcium carbonate to give calcium oxide and carbon dioxide.

Question 34.
What is the importance of evaporation?
Answer:
It is used to separate the non-volatile component from volatile solvent component from a mixture e.g. dye can be obtained from blue-black ink.

Question 35.
What are the applications of centrifugation?
Answer:

1. It is used in diagnostic laboratories to test blood and urine.
2. It is used in diaries and homes to separate butter from cream.
3. It is used in washing machines to squeeze out water from wet clothes.

Question 36.
How will you separate a mixture of:
(a) Iodine and sand?
(b) Ammonium chloride and common salt?
(c) Chloroform and water?
(d) Carbon disulphide and water?
Answer:
(a) By sublimation
(b) By sublimation
(c) By using a separating funnel
(d) By using a separating funnel.

Question 37.
A solution contains 40 g of NaCl in 320 g of water. Calculate its concentration in terms of mass percentage of solution.
Answer:

• Mass of NaCl = 40g
• Mass of water = 320g
• Total Mass of solution = 40 + 320 = 360g
• Mass percentage of solution = 40 / 360 × 100 = 100 / 9 = 11.1

Question 38.
What are the advantages of crystallisation over evaporation?
Answer:

• Some solids decompose on heating to dryness.
• Some solids like sugar may get charred on heating.
• Some impurities may be present in the solution on dissolving the impure solid in a solvent.

Question 39.
Name the separation technique to separate:

1. Insoluble solid insolvent.
2. Solution of solid in liquid.
3. Miscible mixture of liquids.
4. Immiscible mixture of liquids.
5. Mixture of two solids, one of which sublimes

Answer:

1. Filtration, centrifugation
2. Evaporation, crystallisation, distillation
3. Distillation, fractional distillation
4. Separating funnel
5. Sublimation

Question 40.
What is fractional distillation? Give its importance.
Answer:
Fractional distillation. It is the process of separation of a mixture of two or more miscible liquids having very close boiling points (differing by less than 25°C). In this case, distillation is carried out using a fractionating column.
Importance:
1. This process is ised in the separation of petroleum products.
2. It is used to get component gases from air.

Question 41.
A solution of acetone in water contains 5 ml is 50 ml of its aqueous solution. Calculate the volume percentage of the solution.
Answer:

1. Volume of solute = 8ml
2. Volume of solution = 50ml
3. Volume percentage of solution 5/50 × 100 = 10

Question 42.
Define distillation and give its importance.
Answer:
The conversion of a liquid into vapour and condensing the vapours back into liquid is known as distillation.
Importance:
1. To separate two miscible liquids which boil without decomposition and have sufficient differences in their boiling points (more than 30°C).
2. To separate a volatile component of a solution from a non-volatile component.

Question 43.
How are elements classified?
Answer:
The elements can be classified as:
(a) Metals e.g. Cu, Ag etc.
(b) Non-metals e.g. C, S etc.
(c) Metalloids e.g. As, Sb etc.
(d) Noble gases e.g. He, Ne etc.

Question 44.
Which of the following are pure substances and which are mixtures?

1. Air
2. Milk
3. Graphite
4. Gasoline
5. Distilled water
6. Ice
7. Iodised table salt
8. Diamond
9. Oxygen
10. One rupee coin
11. 22 Carat gold
12. 24 Carat gold
13. Steel
14. Iron
15. Solid Iodine

Answer:

1. Air – Mixture
2. Milk – Mixture
3. Graphite – Pure substance
4. Gasoline – Mixture
5. Distilled water – Pure substance
6. Ice – Pure substance
7. Iodised table salt – Mixture
8. Diamond – Pure substance
9. Oxygen – Pure substance
10. One rupee coin – Mixture
11. 22 carat gold – Mixture
12. 24 carat gold – Pure substance
13. Steel – Mixture
14. Iron – Pure substance
15. Solid Iodine – Pure substance

Question 45.
Which one of the substances given ahead is an element, a mixture or a chemical compound. Give one reason in each case:
(a) chlorine
(b) milk
(c) honey
(d) flowers of sulphur
(e) seawater
(f) gun powder
(g) brine
(h) sulphur
(i) apple juice
(j) carbon dioxide
(k) air
(Z) syrup.
Answer:
(a) Chlorine. It is an element made up of only one kind of atom.
(b Milk. It is a mixture of fat, water etc.
(c )Honey. It is a mixture of carbohydrates.
(d Flowers of sulphur. It is an element made up of only sulphur molecules (S8).
(e )Sea Water. It is a mixture of water and dissolved salts.
(f) Gun powder. It is a mixture of sulphur, nitre and charcoal.
(g) Brine. It is a mixture of water and sodium chloride.
(h) Sulphur. It is an element made up of sulphur molecules (S8).
(i) Apple juice. It is a mixture.
(j) Carbon dioxide. It is a compound of carbon and oxygen combined together in the fixed ratio 3 : 8 by mass.
(k) Air. It is a mixture of oxygen, nitrogen and other gases.
(Z) Syrup. It is a mixture.

Question 46.
(a) Name a chemical technique which could be used successfully to separate
1. Iodine crystals from sand.
2. Petrol from kerosene oil.
(b) A pupil decides to separate powdered calcium carbonate from powdered calcium chloride by shaking the mixture with water and filtering. Would this procedure succeed? Explain your answer.
(c) Mixtures are usually heterogeneous, but sometimes homogeneous also.
Give one example each of two different types of mixtures.
Answer:
(a) 1. Sublimation
2. Fractional distillation
(b) Yes, when a mixture of calcium carbonate and calcium chloride is treated with water, calcium chloride dissolves whereas calcium carbonate does not. It is separated by filtration.
(c) Homogeneous mixture, e.g. Brass is a homogeneous mixture of copper and zinc.
Heterogeneous mixture, e.g. common salt and sand.

Question 47.
From the following techniques:
Distillation, filtration, fractional distillation, chromatography, crystallisation, sublimation, evaporation, decantation, sedimentation. Select the method you will use to separate:
(a) the constituents of the colouring matter of ink.
(b) hydrated CuS04 from its aqueous solution.
(c) Grass stains.
(d) Common salt from sea-water.
(e) Petrol from crude oil.
Answer:
(a) Chromatography
(b) Crystallisation
(c) Chromatography
(d) Evaporation
(e) Fractional distillation.

Question 48.
How will you separate a mixtu funnel? Explain with an activity.
Answer:
Take a clean separating funnel and take a mixture of mustard oil and water in it. Allow it to stand for sometime. On standing, two separate layers appears. The lower layer is of water (heavier) and the upper layer is of mustard oil (lighter).

Open the stop cock of the separating funnel and pour out the lower layer of water carefully. Close the stop cock when the water has been removed. Mustard oil is left in the separating funnel.

Very Short Answer Type Questions:

Question 1.
Define pure substance.
Answer:
It is a material containing particles of only one kind having a definite set of properties.

Question 2.
Define mixture.
Answer:
It is a material obtained by mixing two or more elements and or compounds in any ratio.

Question 3.
How will you separate the components of an aqueous solution of sodium chloride?
Answer:
By simple distillation.

Question 4.
Give two examples of homogeneous mixture.
Answer:
Sodium chloride dissolved in water, sugar dissolved in water.

Question 5.
Give two examples of homogeneous mixtures.
Answer:
Iron filings and common salt, common salt and sulphur.

Question 6.
Is the mixture of oil and water, homogeneous or heterogeneous?
Answer:
Heterogeneous.

Question 7.
What is solution?
Answer:
It is a homogeneous mixture of two or more substances whose composition can be changed within certain fixed limits.

Question 8.
Give examples of solid solution.
Answer:
Brass, Bronze.

Question 9.
Give one example of gaseous solution.
Answer:
Air.

Question 10.
Name the components of Brass.
Answer:
Zinc and copper.

Question 11.
Define solute.
Answer:
It is the component of a solution which is present in small amount and which is dissolved in another component called solvent.

Question 12.
Define solvent.
Answer:
It is the component of solution which is present in large amount and in which solute is dissolved.

Question 13.
Name the solute and solvent in an aqueous solution of sugar.
Answer:
Water-Solvent, Sugar-Solute.

Question 14.
In tincture of Iodine, name solute and solvent.
Answer:
Solute-Iodine, Solvent-Alcohol.

Question 15.
In soda water, name solute and solvent.
Answer:
Solute-Carbon dioxide, Solvent-water.

Question 16.
What is the type of air mixture?
Answer:
Homogeneous.

Question 17.
In air name solute and solvent?
Answer:
Solvent-Nitrogen, Solute-Oxygen and other gases.

Question 18.
What is the size of particles of solutions?
Answer:
Less than lnm (10^-9m).

Question 19.
What is saturated solution?
Answer:
It is a solution in which no more of solute can be dissolved at the given temperature and pressure.

Question 20.
What is unsaturated solution?
Answer:
It is a solution in which more of solute can be dissolved at the given temperature and pressure.

Question 21.
What is the concentration of a solution?
Answer:
It gives us the exact amount of solute dissolved in an exact amount of solvent or solution.

Question 22.
What is a suspension?
Answer:
It is a heterogeneous mixture in which small particles of a solid don’t dissolve but remain suspended in the liquid (or gas).

Question 23.
Why is suspension temporary?
Answer:
This is because components of suspension can be saparated by filtration.

Question 24.
Suspended particles in a suspension can be seen with naked eye, why?
Answer:
This is because their sizes are more than 100 run.

Question 25.
What is Tyndall effect?
Answer:
It is the scattering of light by colloidal particles.

Question 26.
How will you prove that milk is a colloidal solution?
Answer:
It shows Tyndall effect.

Question 27.
What is the size of colloidal particles?
Answer:
1 to 100 nm.

Question 28.
How will you separate colloidal particles from solution?
Answer:
By ultra centrifugation.

Question 29.
When do we don’t use filtration?
Answer:
If the solid particles present in solution have very small sizes and can pass through pores of filter paper.

Question 30.
What is the principle of centrifugation of mixtures?
Answer:
Heavier particles settle down and lighter particles float over them.

Question 31.
Where do we use centrifugal machine?
Answer:
In diagnostic laboratory to study urine and blood, in dairies to separate butter and cream from milk, to squeeze water from clothes in washing machine.

Question 32.
On the basis of what principle, two immiscible liquids can be separated?
Answer:
Based upon density.

Question 33.
How can a mixture of sodium chloride and ammonium chloride separated?
Answer:
By sublimation.

Question 34.
Name four substances which undergo sublimations.
Answer:
Ammonium chloride, comphor, naphthalene, anthracene.

Question 35.
How many colours are mixed in a dye?
Answer:
Two or more colours.

Question 36.
Define chromatography.
Ans.wer:
It is the separation of coloured components of a mixture based upon adsorption.

Question 37.
What are the uses of chromatography?
Answer:
1. To separate components of a dye.
2. To separate colours from natural colours, to separate sugar from urine and to separate medicine from blood.

Question 38.
Which type of liquid mixture solutions can be separated by simple distillation?
Answer:
Liquids having large differences in their boiling points.

Question 39.
Which type of liquid mixture solutions are separated by fractional distillation?
Answer:
Liquids whose boiling points differ by less than 25 K.

Question 40.
Give two examples where fractional distillation is used to separate the components of a mixture.
Answer:
Air, petroleum.

Question 41.
What is the function of glass beads in fractionating column?
Answer:
These provide surface for cooling and condensing vapours.

Question 42.
Which type of mixture air is?
Answer:
It is a homogeneous mixture.

Question 43.
What is the boiling point of oxygen?
Answer:
183°C.

Question 44.
What is the boiling point of Argon.
Answer:
186°C.

Question 45.
What is the boiling point of nitrogen?
Answer:
196°C.

Question 46.
When do we use crystallisation for purification?
Answer:
To purify solids.

Question 47.
How will you get pure copper sulphate?
Answer:
By crystallisation.

Question 48.
Why is crystallisation better than simple distillation?
Answer:
In simple distillation, some substances decompose or are burnt and some impurities are left.

Question 49.
How will you get pure water from sea water?
Answer:
By evaporation and simple crystallisation.

Question 50.
How is alum purified?
Answer:
By crystallisation.

Question 51.
What are the changes during chemical change?
Answer:
Chemical decomposition and change of chemical properties.

Question 52.
Name the type of change of combustion?
Answer:
Chemical change.

Question 53.
How is matter classified on the basis of chemical decomposition?
Answer:
Elements and compounds.

Question 54.
Which French scientist proved that element is a fundamental or basic particle of matter?
Answer:
Antonie Lorentz Lavosier.

Question 55.
Which is the basic unit of matter?
Answer:
Element.

Question 56.
Define an element.
Answer:
It is the smallest particle of an element which can’t be decomposed into still smaller particles by chemical reaction.

Question 57.
How are elements classified?
Answer:
Metals, non-metals and metalloids.

Question 58.
Name the metal which is liquid at room temperature.
Answer:
Mercury.

Question 59.
What is metalloid?
Answer:
It shows the properties of both metals and non-metals.

Question 60.
Give two examples of metalloids.
Answer:
Arsenic, antimony.

Question 61.
Give examples of non-metals.
Answer:
Carbon, hydrogen, oxygen, chlorine, bromine etc.

Question 62.
Give examples for metals.
Answer:
Sodium, potassium, copper, iron, gold, silver etc.

Question 63.
How many elements are known till today?
Answer:
112.

Question 64.
How many elements occur in nature?
Answer:
There are 92 natural elements.

Question 65.
How many elements are gases at room temperature?
Answer:
11.

Question 66.
Name five methods to separate mixtures.
Answer:

1. Filtration
2. Crystallisation
3. Sublimation
4. Evaporation
5. Distillation.

Question 67.
How are sugar crystals separated in a sugar factory?
Answer:
By centrifugation process.

Question 68.
The size of colloidal particals is in the range …………….. .
Answer:
1 to 100 run.

Question 69.
Tyndall effect is shown by ……………. .
Answer:
Colloidal particles.

Question 70.
He and Ne are ……………….. gases.
Answer:
Noble.

Question 71.
FeS + H₂S0₄ → …………..
Answer:
FeS + H₂S0₄ → FeS0₄ + H₂S

Question 72.
In a refinery, petrol is obtained from crude oil by the process of …………… .
Answer:
Fractional distillation

Question 73.
Grass stains are removed from the clothing by using ……………. as solvent.
Answer:
Methylated spirit

Question 74.
Common salt is obtained from sea water by the process of ……………. .
Answer:
Evaporation

Question 75.
When caustic soda solution is added to an aqueous solution of copper sulphate, a blue precipitate of copper hydroxide is obtained. The copper hydroxide can be separated from the mixture by the process of ……………….. .
Answer:
Filtration.

Punjab State Board PSEB 9th Class Science Important Questions Chapter 1 Matter in Our Surroundings Important Questions and Answers.

PSEB 9th Class Science Important Questions Chapter 1 Matter in Our Surroundings

Long Answer Type Questions:

Question 1.
Give important characteristics of solid state.
Answer:
Characteristics of solid state:

1. The solids have definite mass, volume and shape.
2. The particles in a solid state are closely packed and the empty spaces in them are negligible.
3. The solids are rigid.
4. A solid does not undergo a change in shape easily.
5. The solids can have any number of free surfaces.
6. There are large attractive forces between the molecules in a solid.
7. Solids have high densities.
8. A solid always tends to resist any change in its structure.
9. The solids don’t show the property of diffusion.

Question 2.
Give important characteristics of the liquid state.
Answer:
Characteristics of the liquid state:

1. A liquid has a definite mass and volume but no definite shape.
2. A liquid can take the shape of a container.
3. Liquids have only one free surface.
4. The vacant spaces between the molecules of liquid are more as compared to solids.
5. The attractive forces between the molecules in a liquid state are lesser than in the solids.
6. The liquids have lower densities as compared to solids.
7. The liquids show the property of diffusion.
8. On heating a liquid, the molecules of it move apart, hence the liquids can expand on heating.

Question 3.
Give important characteristics of gas.
Answer:
Characteristics of a gas:

1. A gas has definite mass but it has neither definite shape nor definite volume.
2. The gases can occupy the whole space available to them.
3. There are negligible attractive forces between the molecules of a gas.
4. The gases have no free surface.
5. There are large vacant spaces between the molecules of a gas.
6. The gases show the property of diffusion.
7. Gases have very low densities as compared to the solids and liquids.
8. The molecules in a gas have high kinetic energies.
9. There is no effect of gravity on the motion of the molecules of a gas.
10. The gases exert equal pressure in all the directions on the walls of the container.
11. The gases are highly compressible.

Question 4.
Give the main postulates of kinetic theory of matter.
Answer:
The main postulates of kinetic theory of matter are:

1. All matter is made up of a large number of extremely small particles called molecules (sometimes atoms or ions).
2. The molecules are always in a state of rapid random motion.
3. The molecules possess kinetic energy.
4. There are attractive forces between the molecules.
5. The attractive forces between the molecules of same kind are called cohesive forces and the attractive forces between the molecules of different kinds are called adhesive forces.
6. The kinetic energy of the molecules increases with the increase in temperature.
7. As the distance between the molecules increases, the magnitude of attractive forces between the molecules decreases.

Question 5.
Distinguish between solids, liquids and gases.
Answer:
The main points of differences are:

Property	Solid	Liquid	Gss
1. Packing of Particles	Most closely packed	Loosely packed	Large vacant spaces between the particles
2. Energy	Particles have least energy	Particles have higher energies than in solids	Particles have high energies
3. Shape	Definite	Take the shape of the container	Take the shape of container
4. Volume	Definite	Definite	No definite volume
5. Density	High	Low	Very low
6. Compressibility	Not possible easily	More than in solids	High
7. Number of free surfaces	Any number	One	No
8. Rigidity	High	Low	Not rigid
9. Fluidity	Don’t show	Show	Maximum fluidity
10. Intermolecular spaces	Very small	Small	Large
11. Thermal expansion	Very low	More than solids	Very large
12. Interparticle attractive forces	Very large	More than in gases	Negligible

Question 6.
How will you explain the three states of matter on the basis of Kinetic Model?
Answer:
Solid: In solids the constituent particles are closely packed and there are large attractive forces between them. Therefore, the particles have low kinetic energies and can’t move from one position to another but they have only vibratory motion. Hence solids have definite shapes and definite volumes.
Examples: Wood, rock, copper, iron, cement, stone etc.

Liquid: In liquids the molecules have higher kinetic energies, distances between the molecules are more and attractive forces between the molecules are small. Therefore, the molecules of a liquid can move from one position to another within the liquid. Hence the liquid can take the shape of the container. But the volume of the liquid remains fixed because the molecules can’t leave the liquid.
Examples: Alcohol, milk, benzene, kerosene oil, petrol etc.

Gas: In gases, the molecules have high kinetic energies, there are large vacant spaces between the molecules and there are negligible attractive forces between the molecules. Therefore, in gases, molecules can move randomly and occupy the whole space available to them. Hence, they don’t have definite volumes and shapes.
Examples: Hydrogen, oxygen, nitrogen, sulphur dioxide, carbon dioxide etc.

Question 7.
Define the terms given below and answer the questions associated with them.
(a) Sublimation: Which of the following substances sublime?
Ice, mercury, dry ice, iodine.
(b) Solid: Why do not solids diffuse in one another?
(c) Liquid: Why do liquids flow?
(d) Freezing point: What is the freezing point of water?
(e) Gas: Why are gases compressible and show diffusion?
Answer:
(a) Sublimation. It is the process in which a solid directly changes into vapour on heating and on cooling the gas directly changes into solid.
Dry ice and iodine sublime.
(b) Solid. It is that state of matter which has definite mass, volume and shape, e.g. sugar, rubber, table, stone etc.
The solids don’t diffuse because in the solid state the vacant spaces between the molecules are very small and molecules of a solid can’t move from one position to another.
(c) Liquid. A liquid is that state of matter which has definite mass and volume but has no definite shape, e.g. milk, petrol, kerosene oil, water etc. Liquids flow because the attractive forces between the molecules of a liquid are very small and the molecules can freely move within the liquid.
(4) Freezing point. It is the temperature at which a liquid changes into a solid state by giving out heat energy. For example, freezing point of water is 0°C.
(e) Gas. It is defined as that state of matter which has definite mass only but has neither definite shape nor definite volume. For example, carbon dioxide, oxygen, hydrogen, ammonia etc.

Short Answer Type Questions:

Question 1.
What are the necessary conditions for a substance to be a
1. Solid
2. Liquid and
3. Gas?
Answer:
1. Solid: The melting point of a substance is above room temperature at the atmospheric pressure.
2. Liquid: The melting point of the substance is below room temperature and boiling point is above room temperature under atmospheric pressure.
3. Gas: The boiling point of the substance is below room temperature under atmospheric pressure.

Question 2.
What are the two new states of matter in addition to solid, liquid and gases states?
Answer:
These are:
1. Plasma: It is produced in stars at very high temperature.
2. Bose-Einstein condensate: It is formed by cooling a gas of extremely low density to super low temperature.

Question 3.
Heat, light, shadow, love, radio waves are not considered as matter, why?
Answer:
This is because these are massless and do not occupy space.

Question 4.
Solids have definite shapes and volumes, why?
Answer:
This is because:

• The vacant spaces between the constituent particles are very small.
• There are large attraction forces between the constituent particles.

Question 5.
List the factors which affect evaporation.
Answer:
These are:

1. Exposed surface area
2. Temperature
3. Humidity in the air
4. Wind speed.

Question 6.
Why is sponge solid although it can be compressed?
Answer:
This is because sponge has minute holes in which there is entraped air. When it is pressed, the air is expelled out.

Question 7.
Rubber band can change its shape, is it a solid?
Answer:
Rubber band is a solid because it changes its shape under force and return to its original state when the applied force is removed.

Question 8.
Indicate which of the following don’t constitute matter?
Car, truck, heat, light, sound, TV waves, radio waves, cement, love, hate, cotton cloth, rock.
Answer:
Heat, light, sound, TV waves, radio waves, love, hate.

Question 9.
What happens when the vacant spaces between the particles of a liquid decreases? How is this possible?
Answer:
The liquid will change into solid. This is carried out by decreasing the temperature or cooling the liquid.

Question 10.
Why do we observe water droplets on the outer surface of a glass containing ice cold water?
Answer:
This is because water vapour present in air, on coming in contact with glass containing ice-cold water lose energy and get converted into liquid state which appear as water droplets.

Question 11.
Why should we wear cotton clothes in summer?
Answer:
This is because in summer, we perspire more and cotton being a good absorber of water, absorbs the sweat and exposes it to the atmosphere for easy evaporation.

Question 12.
Name the change of state during the following changes:
(a) Drying of wet clothes.
(b) Melting of wax when kept in sunshine.
(c) Melting of ice.
(d) Formation of clouds.
(e) Naphthalene balls become smaller when kept in air.
Answer:
(a) Liquid to gaseous state.
(b) Solid to liquid state.
(c) Solid to liquid state.
(d) Liquid to gaseous state.
(e) Solid to gaseous state.

Question 13.
State your observations in the following cases:
(a) Ammonium chloride is heated in a hard glass test tube.
(b) Carbon dioxide is compressed to 70 times the atmospheric pressure.
Answer:
(a) When ammonium chloride is heated in a hard glass test tube, dense white fumes of ammonium chloride fill the tube and deposit to give a white powder near the mouth of the tube (cooler parts).
(b) When carbon dioxide is compressed to 70 atmospheric pressure, it changes into solid state.

Question 14.
What is the difference between gas and vapour?
Answer:

• A gas is a substance which exists in the gaseous state even at room temperature. e.g. oxygen, hydrogen, nitrogen etc.
• A vapour is a substance which can exist in the gaseous state at a temperature lower than that of its boiling point, e.g. water vapour, iodine vapour etc.

Question 15.
Why does a gas fill the container completely?
Answer:
The molecules in a gas are far apart and are in a state of rapid random motion in all possible directions with very high speeds. They move throughout the container in which they are put. Thus, a gas fills the container completely.

Question 16.
How is the liquid state different from the gaseous state?
Answer:
The liquid state is different from the gaseous state in terms of magnitude of attractive forces between the molecules.

Question 17.
Complete the following statements:
(a) The process of liquid changing into solid is called
(b) The process of gas changing into liquid is called
(c) The process of liquid changing into gas is called
(d) The temperature at which a solid changes into a liquid is called
Answer:
(a) Solidification
(b) Condensation or Liquefaction.
(c) Evaporation
(d) Melting point.

Question 18.
What are the uses of interconversion of matter?
Answer:
The uses of interconversion of matter are:

1. Water is converted into steam by heating. Steam is used to run turbines and to generate electricity.
2. Metals are melted by heating and these molten metals can be converted into alloys and cast into machinery parts.
3. Water can be changed into steam as well as ice. Therefore, in nature, ice (or snow), liquid water and water vapour are available.

Question 19.
Give the important properties on the basis of which the three states of matter can be distinguished.
Answer:
The three states of matter can be distinguished on the basis of shape, volume, compressibility, packing of molecules, number of free surfaces etc.

Question 20.
What is the importance of (a) melting point of solid and (b) boiling point of a liquid?
Answer:
(a) A pure solid has a sharp melting point. The impurities decrease the melting point of a solid. Therefore, melting point is used to check the purity of a solid compound.
(b) A pure liquid has a sharp boiling point. The impurities increase the boiling of liquid. Therefore, boiling point is used to check the purity of a liquid.

Question 21.
Give two differences between boiling and evaporation.
Answer:

Boiling	Evaporation
1. It takes place at a fixed temperature called boiling point of the liquid.	1. It takes place at all temperatures.
2. It is a fast process.	2. It is a slow process.

Question 22.
Name five substances which are solids, five substances which are liquids and five substances which are gaseous at room temperature.
Answer:

• Solids: Iron, copper, silver, glass and wood.
• Liquids: Water, milk, mercury, kerosene oil and petrol.
• Gases: Hydrogen, oxygen, carbon dioxide, nitrogen, helium.

Question 23.
Represent interconversion of states by using a figure.
Answer:

Question 24.
State what is observed when iodine is heated in a test tube as shown below.
Answer:

When some crystals of iodine are heated slowly in a test tube, the shiny grey iodine changes directly into vapour without melting. The vapour deposit as grey particles called sublimate on the upper cooler parts of the tube.

Question 25.
Why do gases have neither a definite shape nor a definite volume?
Answer:
In gases
(a) there are large spaces between the molecules of a gas.
(b) the molecules have high kinetic energies and
(c) there are negligible attractive forces between the molecules of a gas.
Hence the molecules in a gas have random motion. Therefore, gases have neither a definite shape nor a definite volume.

Question 26.
Give an experiment to prove that gases are more compressible as compared to liquids.
Answer:

1. Take a 100 ml syringe and close its nozzle by inserting it in a rubber cork or stopper. Remove the piston from the syringe so that whole of syringe is filled up with air.
2. Apply a little vaseline to the piston and insert the piston. Compress piston and it moves downwards easily.
3. Hence air is compressed to a very small volume.
4. Now fill the syringe with water and repeat the above experiment. The piston moves hardly downwards, indicating that there is a negligible compression in volume.
5. The above experiment indicates that gases are highly compressible as compared to liquids.

Question 27.
Which phenomenon occurs during the following changes:

1. Size of naphthalene balls decreases
2. Wax melts in the sun
3. Drying of wet clothes
4. Formation of clouds.

Answer:

1. Sublimation
2. Fusion
3. Evaporation
4. Condensation.

Very Short Answer Type Questions:

Question 1.
Why do things around our surroundings look different?
Answer:
This is due to different shapes, sizes and textures.

Question 2.
Define matter.
Answer:
Everything in this universe is made up of material which occupies space, has mass and can be judged by any one or more of the known five physical senses is called matter.

Question 3.
Give five examples of matter.
Answer:
Air, food, stove, water, plants.

Question 4.
What are Panch Tatva?
Answer:
Early Indian philosophers classified matter in the form of five basic elements called Panch Tatva.

Question 5.
Name the Panch Tatva?
Answer:
Air, earth, fire, sky and water.

Question 6.
How many basic elements were there according to ancient greek philosophers?
Answer:
Four.

Question 7.
What are the basic elements according to greek philosophers?
Answer:
Earth, fire, air and water.

Question 8.
How do modem day scientists classify matter?
Answer:
Based upon their physical properties and chemical nature.

Question 9.
How is matter produced?
Answer:
It is composed of particles.

Question 10.
Why does a large volume of waier get coloured due to a few crystals of potassium permanganate?
Answer:
This is because a single crystal of pota .sium permanganate is made up of millions of tiny particles.

Question 11.
How small are particles of matter?
Answer:
The particles of matter are very very small beyond our imagination.

Question 12.
What is in between particles of matter?
Answer:
There are vacant spaces between particles of matter.

Question 13.
Why do common salt, sugar and dettol dissolve in water?
Answer:
This is because there are large vacant spaces between the particles of matter.

Question 14.
Why does the smell of lighted incence stick spreads out to a large space?
Answer:
This is because particles of a matter are in motion.

Question 15.
Why does common salt dissolve in water?
Answer:
This is because particles of common salt get into the vacant spaces between particles of water.

Question 16.
How will you check purity of honey?
Answer:
If honey falls into water in a stright line, it is a pure honey.

Question 17.
What is the effect of temperature on the particles?
Answer:
Increase in kinetic energy of particles.

Question 18.
Why are particles of a matter always in motion?
Answer:
This is due to kinetic energy.

Question 19.
Define diffusion.
Answer:
It is the mixing up of particles of two or more substances.

Question 20.
What is the effect of temperature on diffusion?
Answer:
Diffusion becomes faster.

Question 21.
What is the effect of pressure on particles of a matter?
Answer:
Pressure keeps particles of matter together.

Question 22.
What are the different stages of matter based upon physical states?
Answer:
Solid, liquid and gas.

Question 23.
Give three characteristics of solids.
Answer:
The solids have definite masses, volumes and shapes.

Question 24.
What is the effect of applied force on solids?
Answer:
The solids retain their shapes on applying force but they break when a large force is applied on them but they don’t change their shapes.

Question 25.
Rubber band can change its shape when stretched? Is it a solid?
Answer:
It is solid because it changes its shape under force and returns to its original shape when applied force is removed. It breaks when a very large force is applied to it.

Question 26.
Sugar, common salt etc. take the shape of containers although these are solids?
Answer:
This is because the shapes of their crystals do not change.

Question 27.
Why does a rubber can be compressed?
Answer:
This is due to the presence of air in the holes present in it and on compression air is expelled out.

Question 28.
What is liquid?
Answer:
A liquid has a definite mass and volume but has no definite shape.

Question 29.
Due to which property aquatic animals survive in water?
Answer:
This is due to the presence of oxygen dissolved in water.

Question 30.
Name the gas which gets dissolved in water and is necessary for plants.
Answer:
Carbon dioxide.

Question 31.
Which form of matter can diffuse in liquids?
Answer:
Solids, liquids and gases.

Question 32.
Liquids show faster diffusion than solids. Why?
Answer:
This is because in liquids there are more vacant spaces and molecules can move freely.

Question 33.
Out of solids, liquids and gases which show maximum compressibility?
Answer:
Gases.

Question 34.
Which compressed gas is used in automobiles?
Answer:
Compressed natural gas (CNG).

Question 35.
Which gas is used as fuel in houses?
Answer:
Liquified Petroleum Gas (LPG).

Question 36.
The smells of perfume and lighted incense stick spread rapidly, why?
Answer:
This is because there are large vacant spaces between the molecules and the molecules are in motion with very high speeds.

Question 37.
What are the different states of water?
Answer:
These are solid-ice, liquid-water and gas-water vapour.

Question 38.
Give characteristics of solids.
Answer:
The solids are generally hard. They cannot be compressed. They have definite shapes and definite volumes.

Question 39.
Give characteristics of liquids.
Answer:
They have definite volumes but have no definite shapes. They can be compressed slightly. They can flow.

Question 40.
Give characteristics of gases.
Answer:
The gases have neither definite shapes nor volumes. They are highly compressible.

Question 41.
Give four examples each of solids, liquids and gases.
Answer:
Solids: Wood, stove, sugar, common salt.
Liquids: Water, milk, oil, alcohol.
Gases: Oxygen, hydrogen, carbon dioxide.

Question 42.
What is the full form of CNG?
Answer:
Compressed Natural Gas.

Question 43.
Why do solids have definite shapes?
Answer:
This is because vacant spaces between molecules of a solid are very small and there are large attractive forces between them.

Question 44.
Why does a tyre can be inflated with large volume of air?
Answer:
This is because gases can bear high pressure.

Question 45.
Why don’t gases have definite shapes and volumes?
Answer:
This is because there are large vacant spaces between the molecules of a gas and these are in motion.

Question 46.
How many states of water are there?
Answer:
Three.

Question 47.
The temperature at which a solid melts is called?
Answer:
Melting point.

Question 48.
What is the SI unit of temperature?
Answer:
Kelvin.

Question 49.
0°C = ………. K.
Answer:
0°C = 273.16 K.

Question 50.
How is kelvin temperature changed to centigrade temperature?
Answer:
By substracting 273 from it.

Question 51.
How is centigrade temperature changed in kelvin temperature?
Answer:
By adding 273 to it.

Question 52.
Define fusion.
Answer:
The process of conversion of solid into liquid is called fusion.

Question 53.
What is the boiling point of water?
Answer:
373 K (100°C).

Question 54.
Define sublimation.
Answer:
It is the process of direct conversion of solid into gaseous state and back without changing into liquid state.

Question 55.
What is dry ice?
Answer:
Solid carbon dioxide.

Question 56.
What is the unit of pressure?
Answer:
Atmosphere (atm).

Question 57.
What is the SI unit of pressure?
Answer:
Pascal (Pa).

Question 58.
What is normal atmospheric pressure?
Answer:
The atmospheric pressure at sea level is called normal atmospheric pressure. It is taken as 1 atmosphere.

Question 59.
How does a liquid change into vapour without boiling?
Answer:
Due to evaporation.

Question 60.
Give one example of evaporation.
Answer:
Drying of wet clothes in sunlight.

Question 61.
Name the process of conversion of liquid into gaseous state without boiling.
Answer:
Evaporation.

Question 62.
Name the factors which increase rate of evaporation?
Answer:
These are increase in surface area, increase in temperature, decrease in humidity.

Question 63.
Why rate of evaporation increases with the increase in temperature.
Answer:
This is because kinetic energy of particles increases.

Question 64.
Why do clothes dry faster with the increase in speed of wind?
Answer:
This is because water vapour evaporates along with air and amount of water vapour decrease near the surface of clothes.

Question 65.
What is humidity?
Answer:
The amount of moisture present in the air is called humidity.

Question 66.
How is vaporisation related to humidity?
Answer:
With the increase in humidity in air, rate of evaporation decreases.

Question 67.
Why are clothes spread out for drying?
Answer:
This increases surface area and hence rate of evaporation increases.

Question 68.
How is cooling related to evaporation?
Answer:
With the increase in evaporation, cooling increases.

Question 69.
Why should we wear cotton clothes in summer?
Answer:
This is because in summer we perspire more and cotton being a good absorber of water, absorbs the sweat and exposes it to the atmosphere for evaporation which causes cooling.

Question 70.
How are particles present in plasma?
Answer:
In plasma, the particles have high energy and are excited. These particles are present in the form of ionised gas.

Question 71.
Wha is present in florescent tube and neon bulb?
Answer:
Plasma.

Question 72.
Why do sun and stars glow?
Answer:
Due to plasma.

Question 73.
Why is plasma produced in stars?
Answer:
Due to high temperature.

Question 74.
How is BEC produced?
Answer:
It is formed by cooling a gas of extremely low density to super low temperature.

Question 75.
Who were awarded Noble Prize for Bose-Einstein Condensate state?
Answer:
Eric A. Cornell, Wolfgang Ketreley and Carl E. Wieman.

Question 76.
Which website is used to get information regarding fourth and fifth state of matter?
Answer:
www.chem4kids.com.

Question 77.
The phenomenon occuring during drying of wet clothes is
Answer:
Evaporation.

Question 78.
The intennolecular spaces are …………. in solids.
Answer:
Large or maximum.

Question 79.
A vapour on cooling changes into …………. and on further cooling changes into ………… .
Answer:
liquid, solid.

Question 80.
Matter changes from one state to another either by raising the or lowering the …………. .
Answer:
temperature, temperature.

Question 81.
A change in which a solid, on heating, directly changes into …………. state and the …………. on cooling again changes into ………… state is called …………… .
Answer:
gaseous, gas, solid, sublimation.

Question 82.
The intermolecular spaces are in …………… solids and ……………. in gaseous.
Answer:
minimum, maximum.

Punjab State Board Syllabus PSEB 10th Class Science Important Questions Pdf in English Medium and Punjabi Medium are part of PSEB Solutions for Class 10.

PSEB 10th Class Science Important Questions in Punjabi English Medium

• Chapter 1 Chemical Reactions and Equations Important Questions
• Chapter 2 Acids, Bases and Salts Important Questions
• Chapter 3 Metals and Non-metals Important Questions
• Chapter 4 Carbon and its Compounds Important Questions
• Chapter 5 Periodic Classification of Elements Important Questions
• Chapter 6 Life Processes Important Questions
• Chapter 7 Control and Coordination Important Questions
• Chapter 8 How do Organisms Reproduce? Important Questions
• Chapter 9 Heredity and Evolution Important Questions
• Chapter 10 Light Reflection and Refraction Important Questions
• Chapter 11 The Human Eye and The Colourful World Important Questions
• Chapter 12 Electricity Important Questions
• Chapter 13 Magnetic Effects of Electric Current Important Questions
• Chapter 14 Sources of Energy Important Questions
• Chapter 15 Our Environment Important Questions
• Chapter 16 Management of Natural Resources Important Questions

PSEB 10th Class Science Important Questions in Punjabi Medium

• Chapter 1 ਰਸਾਇਣਿਕ ਕਿਰਿਆਵਾਂ ਅਤੇ ਸਮੀਕਰਣਾਂ Important Questions
• Chapter 2 ਤੇਜ਼ਾਬ, ਖਾਰ ਅਤੇ ਲੂਣ Important Questions
• Chapter 3 ਧਾਤਾਂ ਅਤੇ ਅਧਾਤਾਂ Important Questions
• Chapter 4 ਕਾਰਬਨ ਅਤੇ ਉਸਦੇ ਯੋਗਿਕ Important Questions
• Chapter 5 ਤੱਤਾਂ ਦਾ ਆਵਰਤੀ ਵਰਗੀਕਰਨ Important Questions
• Chapter 6 ਜੈਵਿਕ ਕਿਰਿਆਵਾਂ Important Questions
• Chapter 7 ਕਾਬੂ ਅਤੇ ਤਾਲਮੇਲ Important Questions
• Chapter 8 ਜੀਵ ਪ੍ਰਜਣਨ ਕਿਵੇਂ ਕਰਦੇ ਹਨ? Important Questions
• Chapter 9 ਅਨੁਵੰਸ਼ਿਕਤਾ ਅਤੇ ਜੀਵ ਵਿਕਾਸ Important Questions
• Chapter 10 ਪ੍ਰਕਾਸ਼-ਪਰਾਵਰਤਨ ਅਤੇ ਅਪਵਰਤਨ Important Questions
• Chapter 11 ਮਨੁੱਖੀ ਅੱਖ ਅਤੇ ਰੰਗ-ਬਰੰਗਾ ਸੰਸਾਰ Important Questions
• Chapter 12 ਬਿਜਲੀ Important Questions
• Chapter 13 ਬਿਜਲਈ ਧਾਰਾ ਦੇ ਚੁੰਬਕੀ ਪ੍ਰਭਾਵ Important Questions
• Chapter 14 ਊਰਜਾ ਦੇ ਸੋਮੇ Important Questions
• Chapter 15 ਸਾਡਾ ਵਾਤਾਵਰਨ Important Questions
• Chapter 16 ਕੁਦਰਤੀ ਸਾਧਨਾਂ ਦਾ ਪ੍ਰਬੰਧ Important Questions

PSEB 10th Class Science Important Questions in Hindi Medium

• Chapter 1 रासायनिक अभिक्रियाएँ एवं समीकरण Important Questions
• Chapter 2 अम्ल, क्षारक एवं लवण Important Questions
• Chapter 3 धातु एवं अधातु Important Questions
• Chapter 4 कार्बन एवं उसके यौगिक Important Questions
• Chapter 5 तत्वों का आवर्त वर्गीकरण Important Questions
• Chapter 6 जैव प्रक्रम Important Questions
• Chapter 7 नियंत्रण एवं समन्वय Important Questions
• Chapter 8 जीव जनन कैसे करते हैं Important Questions
• Chapter 9 आनुवंशिकता एवं जैव विकास Important Questions
• Chapter 10 प्रकाश-परावर्तन तथा अपवर्तन Important Questions
• Chapter 11 मानव नेत्र तथा रंगबिरंगा संसार Important Questions
• Chapter 12 विद्युत Important Questions
• Chapter 13 विद्युत धारा के चुंबकीय प्रभाव Important Questions
• Chapter 14 ऊर्जा के स्रोत Important Questions
• Chapter 15 हमारा पर्यावरण Important Questions
• Chapter 16 प्राकृतिक संसाधनों का संपोषित प्रबंधन Important Questions

Punjab State Board Syllabus PSEB 12th Class Chemistry Important Questions Pdf in English Medium and Punjabi Medium are part of PSEB Solutions for Class 12.

PSEB 12th Class Chemistry Important Questions in Punjabi English Medium

• Chapter 1 The Solid State Important Questions
• Chapter 2 Solutions Important Questions
• Chapter 3 Electrochemistry Important Questions
• Chapter 4 Chemical Kinetics Important Questions
• Chapter 5 Surface Chemistry Important Questions
• Chapter 6 General Principles and Processes of Isolation of Elements Important Questions
• Chapter 7 The p-Block Elements Important Questions
• Chapter 8 The d-and f-Block Elements Important Questions
• Chapter 9 Coordination Compounds Important Questions
• Chapter 10 Haloalkanes and Haloarenes Important Questions
• Chapter 11 Alcohols, Phenols and Ethers Important Questions
• Chapter 12 Aldehydes, Ketones and Carboxylic Acids Important Questions
• Chapter 13 Amines Important Questions
• Chapter 14 Biomolecules Important Questions
• Chapter 15 Polymers Important Questions
• Chapter 16 Chemistry in Everyday Life Important Questions

Punjab State Board Syllabus PSEB 12th Class Biology Important Questions Pdf in English Medium and Punjabi Medium are part of PSEB Solutions for Class 12

PSEB 12th Class Biology Important Questions in Punjabi English Medium

• Chapter 1 Reproduction in Organisms Important Questions
• Chapter 2 Sexual Reproduction in Flowering Plants Important Questions
• Chapter 3 Human Reproduction Important Questions
• Chapter 4 Reproductive Health Important Questions
• Chapter 5 Principles of Inheritance and Variation Important Questions
• Chapter 6 Molecular Basis of Inheritance Important Questions
• Chapter 7 Evolution Important Questions
• Chapter 8 Human Health and Disease Important Questions
• Chapter 9 Strategies for Enhancement in Food Production Important Questions
• Chapter 10 Microbes in Human Welfare Important Questions
• Chapter 11 Biotechnology: Principles and Processes Important Questions
• Chapter 12 Biotechnology and its Applications Important Questions
• Chapter 13 Organisms and Populations Important Questions
• Chapter 14 Ecosystem Important Questions
• Chapter 15 Biodiversity and Conservation Important Questions
• Chapter 16 Environmental Issues Important Questions

Punjab State Board Syllabus PSEB 12th Class Environmental Education Important Questions Pdf in English Medium and Punjabi Medium are part of PSEB Solutions for Class 12.

PSEB 12th Class Environmental Education Important Questions in Punjabi English Medium

• Chapter 1 ਜੈਵਿਕ ਵਿਭਿੰਨਤਾ / ਜੀਵ ਅਨੇਕਰੂਪਤਾ (ਭਾਗ-1) Important Questions
• Chapter 2 ਜੈਵਿਕ ਵਿਭਿੰਨਤਾ / ਜੀਵ ਅਨੇਕਰੂਪਤਾ (ਭਾਗ-2) Important Questions
• Chapter 3 ਜੈਵਿਕ ਵਿਭਿੰਨਤਾ / ਜੀਵ ਅਨੇਕਰੂਪਤਾ (ਭਾਗ-3) Important Questions
• Chapter 4 ਵਾਤਾਵਰਣੀ ਪ੍ਰਬੰਧਣ (ਭਾਗ-1) Important Questions
• Chapter 5 ਵਾਤਾਵਰਣੀ ਪ੍ਰਬੰਧਣ (ਭਾਗ-2) Important Questions
• Chapter 6 ਵਾਤਾਵਰਣੀ ਪ੍ਰਬੰਧਣ (ਭਾਗ-3) Important Questions
• Chapter 7 ਸਟੱਬਲ ਬਰਨਿੰਗ ਦੀਆਂ ਸਮੱਸਿਆਵਾਂ Important Questions
• Chapter 8 ਕਾਇਮ ਰਹਿਣਯੋਗ / ਝੱਲਣਯੋਗ / ਟਿਕਾਊ ਵਿਕਾਸ (ਭਾਗ-1) Important Questions
• Chapter 9 ਕਾਇਮ ਰਹਿਣਯੋਗ / ਝੱਲਣਯੋਗ / ਟਿਕਾਊ ਵਿਕਾਸ (ਭਾਗ-2) Important Questions
• Chapter 10 ਕਾਇਮ ਰਹਿਣਯੋਗ / ਝੱਲਣਯੋਗ / ਟਿਕਾਊ ਵਿਕਾਸ (ਭਾਗ-3) Important Questions
• Chapter 11 ਕਾਇਮ ਰਹਿਣਯੋਗ / ਝੱਲਣਯੋਗ / ਟਿਕਾਊ ਖੇਤੀਬਾੜੀ (ਭਾਗ-1) Important Questions
• Chapter 12 ਕਾਇਮ ਰਹਿਣਯੋਗ / ਝੱਲਣਯੋਗ / ਟਿਕਾਊ ਖੇਤੀਬਾੜੀ (ਭਾਗ-2) Important Questions
• Chapter 13 ਕਾਇਮ ਰਹਿਣਯੋਗ / ਝੱਲਣਯੋਗ / ਟਿਕਾਊ ਖੇਤੀਬਾੜੀ (ਭਾਗ-3) Important Questions
• Chapter 14 ਵਾਤਾਵਰਣੀ ਕਿਰਿਆ (ਭਾਗ-1) Important Questions
• Chapter 15 ਵਾਤਾਵਰਣੀ ਕਿਰਿਆ (ਭਾਗ-2) Important Questions
• Chapter 16 ਵਾਤਾਵਰਣੀ ਕਿਰਿਆ (ਭਾਗ-3) Important Questions
• Chapter 17 ਵਾਤਾਵਰਣੀ ਕਿਰਿਆ (ਭਾਗ-4) Important Questions
• Chapter 18 ਵਾਤਾਵਰਣੀ ਕਿਰਿਆ (ਭਾਗ-5) Important Questions
• Chapter 19 ਵਾਤਾਵਰਣੀ ਕਿਰਿਆ (ਭਾਗ-6) Important Questions
• Chapter 20 ਨਸ਼ਾ-ਮਾੜੇ ਪ੍ਰਭਾਵ-II Important Questions