Class 10

Punjab State Board PSEB 10th Class Science Important Questions Chapter 3 Metals and Non-metals Important Questions and Answers.

PSEB 10th Class Science Important Questions Chapter 3 Metals and Non-metals

Long Answer Typt Questions

Question 1.
Show various steps involved in extraction of metal from an ore by a sketch.
Answer:

Steps involved in the extraction of metals from ores.

Question 2.
Give methods of enrichment of ores.
Answer:
Methods of enrichment of ores. Ores or minerals are mined from earth these are usually contaminated with large amount of impurities which are called gangue. It is necessary to remove these impurities before extraction of metals. By removing gangue the ore is enriched and concentration of metal is increased. Therefore ore in enriched prior to other processes. Methods of removing gangue from ore depends on the difference of physical and chemical properties of both of them.

Enrichment of ore using magnetic method.

Physical methods of enrichment :

• Hydraulic Washing: In this method finely powdered ore is washed with jet of water. In this strong flow of water light gangue particles are washed away where as heavy ore particles settle down, Tin and lead ores are enriched by this method.
• Froth Floatation Method: In this method, mixture of powdered ore and water or some appropriate oil is taken in a tank. Ore particles are coated with oil and gangue particles are wet with water. A blast of compressed air is blown through the pipe of a rotating agitation to produce froth, due to this, mineral particles wetted with oil change into foam and float on the surface of water. Froth containing ore particles is easily transferred to another container sulphides of copper, lead and zinc are enriched by this method.

Chemical Methods: The chemical method used for the concentration of the ore is based on the difference in some chemical property of the metal and the impurities. An example of this method is the concentration of bauxite ore of aluminium.

Concentration of aluminium ore by Bayer’s process: In this method, Bauxite is reduced by treating it with hot sodium hydroxide. It gives sodium meta aluminate (NaAlO₂) which is soluble in water. The solution in filtered to remove the gangue present in the ore because it does not dissolve in sodium hydroxide. NaAlO₂ is allowed to react with hydrochloric acid to obtain Aluminium hydroxide. On strong heating aluminium hydroxide pure aluminium oxide is obtained.

Following reactions take place

Question 3.
Explain General methods used in the extraction of metals.
Answer:
Steps involved in the extraction of metals :

• Enrichment (concentration) of ore.
• Converting concentrated ore into oxide.
• Reduction of metal oxide to obtain metal.
• Refining of impure metal.

1. Concentration :
(A) Hydraulic washing: This method is used for concentration of oxide ores Gangue particles are lighter as compared to ore particles. In this method powdered ore is washed with flowing water. Light gangue particles are washed away with water and heavy ore particles are left.

(B) Froth floatation method: In this method powdered ore is taken in a tank containing water pine oil is also added to it. Sulphide ore is wet with oil and gangue is wet with water.

The water is agitated by blowing compressed air violently, a froth is formed on the surface of water. This froth carries the lighter ore particles along with it to the surface. Gangue particles are heavy and settle to the bottom.

(C) Magnetic separation.

Enrichment of ore using magnetic method.

1. Magnetic method: This method is acceptable for magnetic impurities like iron, cobalt, Nickel etc. Minerals which are of magnetic nature got attracted towards magnetic field. Chromite and pyrolusite ores are enriched by this method. In this method ground ore is placed on a conveyer belt. This belt goes around two rollers one of which is magnetic. When ore comes near the magnetic roller then two heaps of magnetic and non magnetic materials are obtained. Iron ore magnetite is enriched by this method.

(D) Chemical separation: This process is based on the difference between chemical – properties of ores and gangue eg. Bauxite Al₂O₃.2H₂O is impure form of aluminium oxide. It contains Iron (III) oxide (Fe₂O₃) and sand (SiO₂) as main impurities. Due to iron (III) oxide its colour is red brown. Bayer’s process is used to obtain pure aluminium from / bauxite. In this methods powdered ore is mixed with heated sodium hydroxide.
Al₂O₃ (S) + 2NaOH (aq) → 2NaAlO₂ (aq) + H₂O (l)
NaAlO₂ (aq) + 2H₂O (l) → Al(OH)₂ (s) + NaOH (aq)

2. Converting concentrated ore into metal oxide
Roasting: In this process ore is heated in the presence of air to obtain metal oxide. Which can easily be reduced to obtain the metal.

Zinc blende contains zinc sulphide when concentrated zinc blende ore (zinc sulphide) is roasted in air then it gets oxidized to give zinc oxide.

Calcination: In this process ore is heated in the absence of air to remove moisture and volatile impurities.
When carbonate ore is heated it dissociates to give metal oxide.

3. Extracting metals from metal oxide.
To obtain metal from metal oxide it is heated with some reducing agent. To obtain metals zinc, iron, tin etc. their oxides ore heated with carbon which acts as reducing agent.
ZnO(s) + C(s) → Zn(s) + CO(g)

Oxides of metals with medium activity can be reduced by using highly reactive metals like sodium, calcium and aluminium etc.
3MnO₂(s) + 4Al(s) → 3Mn(l) + 2Al₂O₃(s) + heat

4. Electrolytic refining.
In this method impure metal is taken as anode and a thin strip of pure metal is taken in the form of cathode metal salt solution is taken as electrolyte. When electric current is passed through the electrolyte, pure metal from anode dissolves into solution and impurities settle down as anode mud.

Electrolytic refining

Question 4.
(a). How do metals and non-metals react?
Answer:
Metals and non-metals react on the basis of electronic configuration in the valence shell.

Sodium has only one electron in its outer most shell. If it lose its electrons of the M shell then L will become its outermost shell which have complete octet. Nucleus of this atom will have 11 protons but number of electrons is 10, therefore it is positively charged and gives Na+ sodium positive ions. On the other side, there are 7 electrons in the outer most shell of chlorine and it requires one electron to complete its octet. If there is reaction between chlorine and sodium then lost electron of sodium atom is gained by chlorine atom and chlorine atom becomes negatively charged by one unit. Because there are 17 protons in the nucleus of the chlorine atom and there are 18 electrons in K, L and M shells. Therefore, chloride negative ions Cl- is obtained.

Due to opposite charges sodium and chloride ions attract each other and they form strong bonds involving electrostatic forces and form sodium chloride.

Another ionic compound, magnesium chloride is shown in fig.
Formation of NaCl and MgCl₂ by Electron transfer :

Formation of sodium chloride.

Formation of sodium chloride.

Compounds formed by metals and Non-Metals by the transfer of electrons between them are called ionic or electrovalent compounds.

(b) Write four main exceptions from normal properties of metals and Non-Metals.
Answer:

• All the metals are solid at room temperature except mercury. Melting point of metal is usually high but of Gallium and Cesium is low.
• Iodine is a non-metal but still shiny.
• Carbon is a non-metal which can have many forms. Diamond is allotrope of carbon. It is the hardest substance found in nature. Its melting and boiling point are very high. Another allotrope of carbon is graphite which is conductor of electricity.
• Alkali metal (lithium, sodium, Potassium) are so soft that these can be cut by knife. They have low density and low melting point.

Question 5.
How will you differentiate between metals and non-metals?
Answer:
Differences between metals and non-metals on the basis of physical properties :

Difference between metals and non-metals on the basis of chemical properties

Question 6.
Discuss about the extraction of metals
Answer:
Some metals are found in free state in nature. Some metals are found in the form of compounds. Metals at the bottom of reactivity series show very low reactivity. These are found in free state. Gold, silver, platinum and copper are found in free state.

Copper and silver are also found in the form of sulphide and oxide ores. Metals (K, Na, Ca, Mg and Al) which are at the top of reactivity series show very high reactivity that they are never found in free state. Metals at the middle of the reactivity series (Zn, Fe, Pb etc.) are moderately reactive. These are found in the form of oxide, sulphide or carbonate. Some metal ores are found in the form of oxides.

Metals are classified into three types:
(a) least reactive metals
(b) Moderately reactive metals
(c) highly reactive metals.

Reactivity series and metallurgy

Question 7.
What is rust? What are the requirements necessary for its completion? Give ways to prevent rusting of iron?
Answer:
Surface of iron aquires a coating of a brown flaky substance called rust. It is a compound of Iron (III) Oxide and iron (III) hydroxide. It weakens the iron surface. Due to this, a great loss occurs to the iron articles.

The presence of moisture and air is necessary for rusting of iron. This can be proved with an experiment. If we take new shining irons nails in three test tubes as shown, then we find that nails which are in contact with water and air, got rusted. If we completely immerse the nails in water and cover the water surface with oil so that there is no air available for the nails, then nails will not get rusted.

Similarly if we use CaCl, in the test tube absorbs all the moisture so that no moisture is available in this case also, nails will not get rusted.

Ways to Prevent Rusting :

1. Using oil or grease on the surface: If iron surface is covered with oil or grease it does not remain in contact with air and thus rusting is prevented. Machine parts are saved by this method.
2. Using enamel: By painting iron surface, rusting can be prevented. Buses, cars, scooter, motor cycle, windows, trains etc. are saved by this method.
3. Covering with plastic: Iron surface is covered with plastic. Iron furniture is saved by this method.
4. Galvanization: A process of coating thin layer of zinc on iron is called galvanization. This method is used to prevent buckets, tubs, drums, iron sheets etc. from rusting.
5. By electroplating: Iron can be electroplated by metals like Nickle, Chromium, aluminium etc. Rims, handles, bumpers etc. of vehicles are prevented from rusting by this method.
6. By tin: Iron is coated with tin. Ghee canisters, boxes used for packing food are tinned.
7. Converting to steel: Iron can be preverted from rusting by converting it into steel.

Question 8.
Explain General properties of ionic compounds.
Answer:
General properties of ionic compounds are given below:

• Physical nature: Due to strong force of attraction between positive ions and negative ions, ionic compounds are solid. They are brittle and break on pressing.
• Melting and boiling point: They have high melting and boiling points. Because a large amount of energy is required to break the strong inter ionic attraction.
• Solubility: Ionic compounds are normally soluble in water but are insoluble in Kerosene, Petrol etc.
• Electric Conductivity: In solid form ionic compounds do not conduct electricity because of strong and firm structure. Movement of ions is not possible. But ionic compounds can conduct electricity in molten state, because electrostatic force of attraction becomes very weak due to heat energy. Therefore ions can move freely and electric current can pass through it. Mobility of charged particles is necessary for conduction of electricity in a solution. Ions are present in aqueous solution of ionic compounds. When electric current is passed through the solution then ions start moving towards the opposite electrodes.

Question 9.
What is an alloy? Magnetic iron oxide explain the objective of their formation?
Answer:
Alloy: An alloy is a homogeneous mixture of a metal with another metal or non-metal, e.g. solder is an alloy of lead and tin (Pb and Sn). Stainless steel, solder, brass, bronze, bell metal etc.

Uses of alloys :

• For increasing hardness: Iron is mixed with carbon to form stainless steel which is harder than iron. Copper is mixed with gold and lead is mixed with silver to make them hard. Duralium is an alloy made from aluminium and is very hard.
• Increasing strength: Steel, Duralium are hard as well as strong.
• Preventing Corrosion: By making stainless steel an alloy of iron, which do not get rusted.
• To produce sound: Bell metal is an alloy of copper and tin used to produce loud sound.
• To lower melting point: An alloy of Bismuth, tin and lead has low melting point.
• Moulding: Bronze and type metal.
• For change in colour: Aluminium bronze is an alloy of copper and aluminium is of golden colour.
• Domestic uses: Alloys are used in homes, factories, offices etc. e.g. utensils, almirahs, fans, refrigerators elements etc. are made up of alloys.

Question 10.
Explain the activity series of metals.
Answer:
All metals have different rates of activity. Some metals like sodium, potassium and calcium etc. are highly reactive. These metals combine with oxygen to form oxide and react with hydrogen to form hydrides. Some metals are compratively less reactive e.g. iron, zinc etc. Some metals are least reactive e.g. gold, silver. Reactivity of metals depends on their ability to lose electrons, Metals are arranged in a list in decreasing rate of their activity.

Metals which are above hydrogen are more reactive and those below hydrogen are lower in reactivity and are found in free state. In this series potassium is the most reactive metal in this series.

Short Answer Type Questions

Question 1.
Name two metals which are good conductors of heat and electricity. Name metals which are highly and least conducting with reference to heat.
Answer:
Copper and aluminium are good conductors of electricity and heat. Silver is very good conductor of heat whereas lead is not a good conductor of heat.

Question 2.
Define ductility with example.
Answer:
Property of drawing thin wires from a metal is called ductility. Gold is the highest ductile metal. We can draw 2 km long wire from 18 carat gold.

Question 3.
What is electrical conductivity? Name the metals which have the highest conductivity, less than this and the lowest conductivity.
Answer:
It is the ease with which electric current can flow through a metal. Those metals which offer very low resistance to the flow of current they have high conductivity. Silver, copper are very good conductors of current then comes gold, aluminium and tungsten. Lead and iron have least conductivity i.e., they offer very high resistance to the flow of current.

Question 4.
Which property of metals give them characteristic chemical properties?
Answer:
Metals form positive ions by loosing electrons. This property of formation of ions by the metals give them characteristics chemical properties, e.g., Mg form Mg ion by loosing two electrons :
Mg → Mg²⁺ + 2e^–

Question 5.
Ionic compounds are found in which state? Comment on the melting and boiling point of ionic compounds.
Answer:
Compounds which are formed by the transfer of electrons from metals to Non¬Metals are called ionic or electrovalent compounds e.g., NaCl, LiCl, CaCl₂, CaO, MgCl₂. Ionic compounds have very high melting and boiling points because a large amount of energy is required to break the strong inter-ionic attractions.

Question 6.
What is difference between minerals and ores?
Answer:

Question 7.
How are the metals extracted, which are at the top of reactivity series?
Answer:
Metals which are towards the top of reactivity series are sodium, calcium, magnesium, aluminium. There are very reactive. These metals can not be obtained by heating them with carbon. These have more affinity towards oxygen, therefore these are extracted by electrolytic reduction. Sodium, magnesium and calcium are obtained by the electrolysis of their molten chlorides. Metals got deposited at cathode and chorine is liberated at anode.
At cathode : Na⁺ + e^– → Na
At anode : 2Cl^– → Cl₂ + 2e^–

Aluminium is obtained by the electrolytic reduction of aluminium oxide.
At cathode ; Al³⁺ + 3e^– → Al

Question 8.
How the metals, which are in the middle of the activity series extracted?
Answer:
Metals which are in the middle of the activity series are iron, zinc, lead, copper etc. These are found in the form of sulphides or carbonates. It is easy to obtain metals from their oxides compared to sulphides or carbonates. Therefore before extraction metal sulphide or carbonates are converted into their oxide. Sulphide ores are converted into metal oxides by heating in the presence of air. This is known as roasting. Carbonate ores are heated in limited supply of air to convert them into oxides. This is known as calcination. Following reactions take place during roasting and calcination of zinc.


Then by using carbon as reducing agent, metal is extracted from metal oxide, e.g. when Zinc oxide is heated with carbon it gets reduced to give zinc.

In addition to using carbon for reduction, displacement reaction can be used to extract metals. More reactive metals like sodium, calcium, aluminium etc. can be used as reducing agents because these can displace atoms which are below them in the reactivity series. For example, when mangnese dioxide is heated with aluminium powder then following reaction takes place.

Question 9.
How will you extract metals which are low in the activity series?
Answer:Metals low in the activity series are less reactive and can be obtained from metal oxides simply by heating. Cinnabar (Hgs) an ore of mercury (Hg) when heated change to mercuric oxide (HgO), on heating it further it is reduced to mercury.

Question 10.
Explain the reactions of metals with water.
Answer:
On reacting with water, metals form metal oxide and produce hydrogen. These dissolve in water to form metal hydroxide. But all metals do not react with water.

Metals like sodium and Potassium react with cold water, vigorously. The reaction of sodium and Potassium is very vigorous and exothermic that hydrogen produced starts burning simultaneously.
2K (s) + 2H₂O (l) → 2KOH (aq) + H₂(g) + heat
2Na (s) + 2H₂O (l) → 2NaOH (aq) + H₂(g) + heat

Reaction of calcium with water is slow. Heat produced in this reaction is not enough to burn the hydrogen produced in the reaction.
Ca (s) + 2H₂O(l) → Ca (OH)₂ + H₂(g)

Metals like iron, aluminium, zinc etc. do not react with cold water and not even with hot water. But they react with steam to form metal oxide and produce, hydrogen.
2Al(s) + 3H₂O(g) → Al₂O₃(S) + 3H₂(g)
3Fe(s) + 4H₂O(g) → Fe₃O₄(s) + 4H₂(g)
Metals like lead, copper, silver and gold etc. do not react with water.

Question 11.
How do metals react with :
1. Oxygen
2. Dilute acids
3. Chlorine
4. Hydrogen.
Answer:
I. Reaction of metals with oxygen: Metals combine with oxygen to form metal oxides. Metal atoms lose their loosely bound electrons to form positive ions where as oxygen atoms gain electrons to form negative oxide ions. These metal oxide are basic in nature. Since all metals have different level of reactivity therefore they combine with oxygen at different temperatures.
1. Na and K Combine with oxygen at normal temperature to form oxides which dissolve in water to form hydroxide.
4 Na (s) + O₂(g) → 2Na₂S(s)
Na₂O(s) + H₂O → 2NaOH (or)

2. If magnesium is burned in air it forms magnesium oxide.
Mg → Mg²⁺ + 2e-
O + 2e^– → O^2-
Mg²⁺ + O^2- → MgO

3. Copper and iron combine with oxygen at high temperature in dry air.

II. Reaction of metals with dilute acids. Metals reacts with dilute acids to produce hydrogen gas. Rate of reactivity is different.
1. Na, K, Zn, Mg, Fe etc. are reactive in decreasing order.
2Na + HCl → 2NaCl + H₂ ↑
Mg + 2HCl → MgCl₂ + H₂↑
Zn + H2SO₄ → ZnSO₄ + H₂↑

2. Dilute nitric acid reacts with metals like Cu, Ag, Pb, Hg to form NO (nitrogen oxide).
Cu + 8HNO₃ → 3Cu (NO₃)₂ + 2NO + 4H₂O
3Ag + 4HNO₃ → 3AgNO₃ + NO + 2H₂O

3. Dilute nitric acid reacts with Mg and Mn to produce hydrogen gas.
Mg + 2HNO₃ → Mg (NO₃)₂ + H₂ ↑

4. Gold and platinum do not react with dilute acids.

III. Reaction of metals with chlorine. Metals combines with chlorine to form electrovalent chlorides.
Ca + Cl₂ → CaCl₂

IV. Reaction of metals with hydrogen. Reactive metals like Na, K, Ca etc. react with hydrogen to form hydrid.
2Na + H₂ → 2NaH
Ca + H₂ → CaH₂

V. Reaction of metals with water:
1. Water at normal temperature react with Na, K and Ca to liberate hydrogen gas.
2Na + 2H₂O → 2NaOH + H₂ ↑
Ca + 2H₂O → Ca (OH)₂ + H₂ ↑

2. Mg, Zn and Fe react with boiling water to form oxide.
Mg + H₂O → MgO + H₂ ↑
3Fe + 4H₂O → Fe₃O₄ + 4H₂ ↑

Question 12.
What is roasting? When do you use it?
Answer:
Roasting. After enrichment of ore, it is heated in the presence of dir, this process is called roasting sulphides or carbonates of some metals are converted into oxides, because extraction of metal is easy from oxides. Carbonates and sulphides of zinc and lead are converted into oxides by roasting.

Question 13.
If a copper plate remains immersed in silver nitrate solution for some time then what happens? Write the ionic equation for the reaction.
Answer:
Copper is more reactive than silver. Copper will displace silver from the solution and silver gets deposited on copper. Colour of the solution becomes blue.

Question 14.
Copper sulphate solution is stored in an iron container. After some days holes were seen in the container. Write the reaction. Explain the reaction on the basis of activity series.
Answer:
Iron is more reactive than copper and is placed before copper in the activity series. Therefore iron can displace copper from copper sulphate solution, due to this reaction holes were seen in the container.
CuSO₄ + Fe → FeSO₄ + Cu
Cu²⁺ (aq) + Fe(s) → Fe²⁺ (aq) + Cu(s)
Thus iron displaced copper.

Question 15.
Why copper becomes green if left open in air. Why?
Answer:
Copper reacts with moist carbon dioxide which is present in air. This makes its surface dull and a green layer is seen on the surface of copper. This green substance is copper carbonate.

Question 16.
What is 24 carat gold?
Answer:
Pure gold is called 24 carat gold. It is very soft. It can be used to make ornaments. Small amount of silver or copper is mixed with it to make it harder. In our country usually 22 carat gold is used to make ornaments. This means 22 pure gold is mixed with 2 parts of copper or silver.

Question 17.
Which process is used for the enrichment of sulphide ore. Explain in brief two steps involved in the extraction of metal from enriched sulphide ore.
Answer:
Sulphide ore is finely grounded to get powder. This is then enriched by using ‘Froth floation process’.

Steps involved in the extraction of metal from enriched sulphide ore :
1. Roasting: Enriched ore is heated in the presence of air to get oxides. This process is called roasting.

2. Reduction. Oxide of the enriched ore is heated with reducing agent to extract the metal.

Question 18.
Give differences :
(i) Hydraulic washing and liquation.
Answer:

(ii) Electrolytic reduction and reduction by carbon.
Answer:

Question 19.
An alloy of yellow’ colour is made up of two metals A and B. When this alloy was dipped in dilute sulphuric acid, a layer dissolved in acid and formed colourless solution. B did not dissolve in it and the surface of alloy attained red brown colour. What is A and B?
Answer:
Yellow coloured alloy is brass which is mixture of zinc and copper. In this A is zinc and B is copper.
Zn + H₂SO₄ → ZnSO₄ + H₂

Question 20.
Sulphur dioxide (SO₂) gas is produced when a certain ore is heated. Write the method involved in the extraction of metal from this ore.
Answer:
SO₂ gas is produced when copper pyrites an ore of copper is heated.

Following steps are involved in the extraction of metal from this ore :
1. Ore is ground to get powder. It is mixed with water and pine oil. Compressed air is blown to separate impurities. This way ore gets enriched, this method is called froth floatation method.

2. Now the enriched ore is roasted. A part of CuS converts to CuO

Copper is in liquid state and is purified by electric refining.

3. Electrical refining. In this process impure copper rod is taken as anode and pure copper plate is taken as cathode. Electric current is passed through copper sulphate solution in the presence of acid

Question 21.
What is Thermite process? Write its uses.
Answer:
Some displacement reactions are highly exothermic. The quantity of heat produced is so high that metals obtained are in molten state. When Iron (III) oxide (Fe₂O₃) reacts with aluminium then a large amount of heat is produced.
Fe₂O₃(s) + 2Al(s) → 2Fe(l) + Al₂O₃(s) + heat

This is known as thermite process. This process is used to weld the rails and to join the cracks in machines.

Question 22.
Give five uses of non-metals.
Answer:

• Hydrogen is used in the preparation of vegetable oil.
• Carbon is an important non-metal which is main constituent of vitamins, proteins, carbohydrates, enzymes etc. Graphite is used as an electrode in various cells.
• Nitrogen is used in ammonia, Nitric acid and fertilizers. Its presence in air controls the rate of combustion.
• Presence of oxygen is the base of our life. Combustion is also possible in the presence of oxygen.
• Sulphur is used in many medicines and is also used to make explosives.

Question 23.
Differentiate Roasting and Calcination.
Answer:

Question 24.
How is ionic compound sodium chloride, forms from sodium and chlorine?
Answer:
Sodium and chloride ions are oppositely charged and thus attract each other
They are bound together by strong electrostatic force of attraction and exist in the form of sodium chloride (NaCl). Sodium chloride does not exist as a molecule but as a set of ions :

Question 25.
Ionic compounds are insulators when in solid state whereas when in aqueous solution they become conductors. Why?
Answer:
There exist a strong force of attraction between positive and negative ions of the ionic compounds, due to which these compounds are solid and hard. Due to their firm and rigid structure ions cannot move. But in molten state or in aqueous solution the force between opposite ions become weak and the ions can move freely. Therefore electricity can pass through ionic compounds when in liquid form.

Question 26.
What is aqua regia? Explain.
Answer:
Aqua regia is a mixutre of concentrated hydrochloric acid and concentrated nitric acid in the ratio of 3 : 1. It can dissolve gold where no single acid can do this. Aqua regia (Latin word for Royal water) is highly corrosive and fuming liquid. It can also dissolve platinum.

Question 27.
Give two main ores of aluminium. Also give two alloys of aluminium.
Answer:
Two ores of aluminium are :

1. Bauxite, Al₂O₃. 2H₂O
2. Cryolite, Na₃ (AlF₆).

Two alloys of aluminium are :

1. Duralium
2. Magnalium.

Question 28.
Give uses of pure metals.
Answer:

• Copper and aluminium wires are used in the transmission of power (electricity).
• Utensils, Machines etc. are made up of iron, aluminium and copper.
• Gold and silver are used to make ornaments, these are also used in sweets in the form of silver foil.
• Metals like cadmium, titanium, zinconium etc. are used in nuclear energy and space science projects.
• Aluminium foil is used to wrap eatables.
• Titanium and its alloys are used in airplane, airplane structure and engine, chemical reactor.
• Metals are used in broken bones and body parts.

Question 29.
Which gas is produced, when reactive metals come in contact with dilute hydrochloric acid? Write the chemical reaction between iron and dil. H₂SO₄.
Answer:
When reactive metals come in contact with dil. hydrochloric acid then (H₂) hydrogen gas is produced.
Hydrogen gas is produced when iron reacts with dil. H₂SO₄.
Fe + H₂SO₄ → FeSO₄ + H₂ ↑

Question 30.
What is the function of cryolite in the electrolytic reduction of alumina?
Answer:
Cryolite has two functions in the extraction of aluminium :

• To reduce the melting point of alumina.
• Alumina is bad conductor of electricity on mixing cryolite (Na₂AlF₃), Al²⁺ ions are produced from alumina.

Question 31.
How do iron and aluminium react with water?
Answer:
Aluminium and iron do not react with cold or hot water. But react with steam to form metal oxide and hydrogen.
2Al(s) + 3H₂O(g) → Al₂O₃(s) + 3H₂(g)
3Fe(s) + 3H₂O(g) → Fe₃O₄(s) + 3H₂(g)

Question 32.
What happen when :
(i) Iron oxide is heated with coke?
Answer:
Iron oxide is readuced to iron.

(ii) Magnesium is treated with dilute sulphuric acid?
Answer:
Hydrogen is produced

(iii) Zinc is added to blue vitriol solution?
Answer:
Blue colour of solution gradually faders away

Question 33.
What is rust? Explain it with the help of a chemical reaction.
Answer:
If iron is left open in moist air, a brown layer is produced on its surface. This brown coloured layer is of Ferric oxide and ferric hydroxide. This is called rust. This makes iron weak.
4Fe + 3O₂ + 3H₂O → Fe₂O₃ + 2Fe(OH)₃

Question 34.
Write names of main alloys and their constituents?
Answer:

Question 35.
Write the names of metals found in Bronze and Duralium, give uses of these alloys.
Answer:
Bronze. It is 90% copper and 10% tin. It is used in idols, medals, coins and vessels used for cooking food.
Duralium. It consists of 95% aluminium, 4% copper, 0.5% magnesium and 0.5% manganese. It is used in aeroplanes, space crafts, kitchen vessels.

Question 36.
What is rust? What is its chemical formula?
Answer:
When iron is left open in air, then a layer of iron oxide is formed on the surface of iron. This brown matter is rust. It corrodes the metal. Its chemical formula is Fe₂O₃. xH₂O.

Question 37.
What are metals?
Answer:
The elements which are on the left and in the middle of the periodic table and have metallic lustre are called metals. These are usually ductile, malleable, good conductor of electricity and heat, hard and have high density. They form basic oxides. Examples of metals are gold, iron, silver, copper, platinum etc.

Question 38.
What is ihe reason of catching fire by potassium and sodium on their own?
Answer:
Potassium and sodium reacts with water vigorously and violently. The reaction is very violent and highly exothermic that hydrogen produced in the reaction catches fire on its own.

Question 39.
Observe the figure given below and name the gas produced. Also give the chemical equation.

Answer:
Hydrogen gas is produced

Question 40.
What is indicated by the following figure?
Or
With the help of a labelled diagram prove that both oxygen/air and water are necessary for rusting of iron.

Answer:
Both air and moisture are required for rusting of iron.

Question 41.
Why the substance obtained by mixing small amount of carbon in iron is used largely for various purposes?
Answer:
When small amount of carbon is mixed with iron it changes to steel. This is stronger than iron. It can be used in ships, vehicles, dams.

Question 42.
Write a chemical equation for the reaction taking place in the test tube. How does the colour of solution change? What is change in colour of iron nails?

Answer:

The colour of the solution changes from blue to light green. The colour of Iron nails changes from grey to brown.

Very Short Answer Type Questions

Question 1.
Give one example of metal which is liquid at room temperature.
Answer:
Mercury.

Question 2.
Name one metal and one non-metal which is liquid at room temperature.
Answer:
Metal-Mercury.
Non-Metal—Bromine

Question 3.
Name one non-metal which has bright lustre.
Answer:
Iodine.

Question 4.
Name one non-metal which does not have bright.
Answer:
Phosphorus.

Question 5.
Which of the following metal are liquid at body temperature (37° C): Gallium, Magnesium, Caesium, Aluminium.
Answer:
Gallium and Caesium.

Question 6.
Name one non-metal which is a good conductor of electricity?
Answer:
Graphite (Carbon).

Question 7.
Arrange the following metals in the decreasing order of reactivity,
Fe, Zn, Cu, Na, Ag.
Answer:
Na > Zn > Fe > Cu > Ag.

Question 8.
Out of Sodium, Calcium, Aluminium, Copper and Magnesium name the metal which reacts with
(i) Boiling water
Answer:
Magnesium

(ii) Steam.
Answer:
Copper.

Question 9.
Sodium metal is kept under kerosene oil, why?
Answer:
This is because sodium reacts with moist air as well as water.

Question 10.
A non-metal X, exists in two forms Y and Z. Y is the hardest substance and Z is a poor conductor of electricity. What are X, Y and Z?
Answer:
Y = Diamond Z = Graphite X = Carbon
Y and Z are allotropic forms of carbon.

Question 11.
An element, A form two oxides AO and AOa. AO is neutral and AO₂ is acidic : Indicate whether A is metal or non-metal.
Answer:
A is non-metal.

Question 12.
Name the reaction to convert metal into its oxide .
Answer:
Oxidation.

Question 13.
Ionic solids have high melting points, why?
Answer:
In ionic solids, there are strong electrostatic forces of attraction between the oppositely charged ions and a large amount of energy required to overcome these forces.

Question 14.
An element X reacts with oxide to form oxide, X₂O which dissolves in water and turns red litmus solution blue. Give the nature of oxide and indicate X is metal or non-metal.
Answer:
X₂O is basic. X is metal.

Question 15.
What is the nature of metal oxides?
Answer:
Basic.

Question 16.
Name two noble metals.
Answer:
Gold and platinum.

Question 17.
Name an ore of mercury.
Answer:
Mercury sulphide (Hgs).

Question 18.
Name two metalloids.
Answer:
Arsenic, antimony.

Question 19.
Metals lose lustre when placed in air, why?
Answer:
This is because their surfaces are covered with oxides, carbonates or sulphide layer’s .

Question 20.
Name two metals which can be cut with a knife.
Answer:
Sodium and potassium.

Question 21.
Why do metals aquire different shapes?
Answer:
This is due to malleability and ductility of metals.

Question 22.
Name the metal which is poor conductor of heat.
Answer:
Lead.

Question 23.
Name the metal which offers resistance to the flow of electricity.
Answer:
Mercury.

Question 24.
Which of the following metals can be drawn into wires?
Answer:
Cu, Al, Fe, Pb.

Question 25.
Name four non-metals which are solid at room temperature.
Answer:
Carbon, Sulphur, Phosphorous, and iodine.

Question 26.
Name the elements which are present in abundance in earth’s crust.
Answer:
Oxygen and silicon.

Question 27.
What are alkalies? Give one example.
Answer:
Alkali. It is a metal hydroxide soluble in water Example : Sodium hydroxide (NaOH).

Question 28.
Name two amphoteric oxide.
Answer:

1. Aluminium oxide (Al₂O₃)
2. Zinc Oxide (ZnO)

Question 29.
What happens when magnesium is heated to ignition temperature?
Answer:
Magnesium burns with white light producing magnesium oxide.

Question 30.
Name the metal which does not react with dil. HCl.
Answer:
Copper.

Question 31.
Name two metals which react with hydrogen.
Answer:
Sodium and potasium.

Question 32.
Give the reaction when a piece of Calcium reacts with water.
Answer:
Ca + 2H₂O → Ca (OH)₂ + 4H₂.

Question 33.
Give the reactions when red hot iron reacts with steam.
Answer:
Ca + 4H₂O → Fe₃O₄ + H₂.

Question 34.
Why is zinc oxide called amphoteric oxide?
Answer:
This is because zinc oxide reacts with both acid as well as base.

Question 35.
The metals Na, K and Ca react with hydrogen to form hydroxide but other metals don’t, why?
Answer:
This is because Na, K and Ca are highly reactive metals.

Question 36.
Give the reactions which occur when zinc plate is added to copper sulphate solution.
Answer:
Zn + CuSO₄ → ZnSO₄ + Cu.

Question 37.
Out of the metals, Na, Cu, Au, which is
(i) Most reactive and
Answer:
Most reactive metal-Sodium (Na)

(ii) Least reactive?
Answer:
Least reactive metal-Gold (Au).

Question 38.
Arrange the following metals in the decreasing order of reactivity, Zinc, Mercury and Aluminium.
Answer:
Al < Zn < Hg.

Question 39.
Name two metals which occur in free state in nature.
Answer:
Gold and Platinum.

Question 40.
Define corrosion of metals.
Answer:
It is the interaction of surface of metal with air and moisture forming a layer of oxide, halide or carbonate layer on its surface.

Question 41.
Name a metal which undergoes corrosion in air.
Answer:
Iron.

Question 42.
Name two metals which are not corroded easily.
Answer:
Gold and silver.

Question 43.
Why does copper utensils turn green on exposure to air?
Answer:
Copper reacts with oxygen, carbon dioxide and moisture to form a green coloured compound (basic copper carlxmate):

Question 44.
Name two metals which are both malleable and ductile.
Answer:

1. Copper
2. Aluminium.

Question 45.
Name the most abundant metal in the earth’s crust.
Answer:
Aluminium.

Question 46.
Name the metal that gives a green coating when exposed to moisture.
Answer:
Copper.

Question 47.
Which is the most lightest metal known to us?
Answer:
Lithium.

Question 48.
Name two metals which occur in free state in nature.
Answer:

1. Gold
2. Platinum.

Question 49.
Name one of the most common ore of aluminium.
Answer:
Bauxite (Al₂O₃. 2H₂O).

Question 50.
What is an amalgam?
Answer:
An amalgam is an alloy of mercury with some other metals.

Question 51.
Name two metals which :
(a) readily burn in air an
Answer:
Metals which readily burn in air are :

1. sodium
2. magnesium.

(b) do not burn.
Answer:
metals which do not burn readily in air are :

1. Copper
2. iron.

Question 52.
Name the metal which is best conductor of electricity.
Answer:
Silver.

Question 53.
Name one metal which reacts with cold water.
Answer:
Sodium.

Question 54.
Name one metal
(i) more reactive than hydrogen and
Answer:
Sodium

(ii) less reactive than hydrogen.
Answer:
Silver.

Question 55.
Write the chemical name of any one compound ore of sulphur.
Answer:
Zinc sulphide (ZnS).

Question 56.
Name the metal used in galvanisation of iron.
Answer:
Zinc.

Question 57.
The metal which is found in nature in the free state is
Answer:
Gold and Platinum.

Question 58.
What chemical process is used for obtaining a metal from its oxide?
Answer:
Reduction process.

Question 59.
Which metals do not corrode easily?
Answer:
The metals which are not attacked by air and moisture don’t corrode easily.

Multiple Choice Questions :

Question 1.
The non-metal which is liquid at room temperature is:
(A) Chlorine
(B) Bromine
(C) Fluorine
(D) Iodine.
Answer:
(B) Bromine

Question 2.
Most reactive metal is:
(A) Na
(B) Mg
(C) Au
(D) K
Answer:
(D) K

Question 3.
The property due to which metals can be beaten into sheets is :
(A) Malleability
(B) Ductility
(C) Metallic lustre
(D) Hardness.
Answer:
(A) Malleability

Question 4.
The axnphoteric oxide is:
(A) ZnO
(B) BaO
(C) K2O
(D) Na2O.
Answer:
(A) ZnO

Question 5.
Copper gets covered with green layer when exposed to air due to the formation of:
(A) CuSO₄
(B) CuCO₃. Cu(OH)₂
(C) Cu (NO₃)₂
(D) CuO.
Answer:
(B) CuCO₃. Cu(OH)₂

Question 6.
During galvanisation, the metal whose layer is deposited is:
(A) Gallium
(B) Aluminium
(C) Zinc
(D) Silver.
Answer:
(C) Zinc

Fill in the blanks:

Question 1.
Brass is an alloy of copper and ____________
Answer:
Zinc.

Question 2.
____________ is the best conductor of electricity.
Answer:
Silver.

Question 3.
All the ores are ____________
Answer:
Minerals.

Question 4.
Copper can be refined by ____________
Answer:
Electrorefining.

Punjab State Board PSEB 10th Class Science Book Solutions Chapter 3 Metals and Non-metals Textbook Exercise Questions and Answers.

PSEB Solutions for Class 10 Science Chapter 3 Metals and Non-metals

PSEB 10th Class Science Guide Acids, Bases and Salts Textbook Questions and Answers

Question 1.
Which of the following pairs will give displacement reactions :
(а) NaCl solution and copper metal
(b) MgCl₂ solution and aluminium metal
(c) FeSO₄ solution and silver metal
(d) AgNO₃ solution and copper metal?
Answer:
(d) AgNO₃ solution and copper metal?

Question 2.
Which of the following methods is suitable for preventing an iron frying pan from rusting :
(a) applying grease
(b) applying paint
(c) applying a coating of zinc
(d) all of the above :
Answer:
(c) applying a coating of zinc

Question 3.
An element reacts with oxygen to give a compound with a high melting point. This compound is also soluble in water. The element is likely to be :
(a) calcium
(b) carbon
(c) silicon
(d) iron.
Answer:
(a) calcium

Question 4.
Food cans are coated with tin and not with zinc because :
(а) zinc is costlier than tin
(b) zinc has a higher melting point than tin
(c) zinc is more reactive than tin
(d) zinc is less reactive than tin.
Answer:
(c) zinc is more reactive than tin

Question 5.
You are given a hammer, a battery, a bulb, wires and a switch.
(i) How could you use them to distinguish between samples of metals and non-metals?
(ii) Assess the usefulness of these tests in distinguishing between metals and non-metals.
Answer:
(i) Set up the electric circuit as shown below :

To distinguish between metals and non-metals on the basis of their electrical conductivity.

Insert the sample to be tested between clips A and B
If the bulbs glows, the sample is metal.
If the bulb does not glow, the sample is non-metal.
Thus metals are good conductors of electricity whereas non-metals are poor conductors of electricity.

(ii) If a substance produces a sound when struck beating with a hammer, it is a metal and if no sound is produced, it is a non-metal.
Metals are sonorous whereas non-metals are non-sonorous.

Question 6.
What are amphoteric oxides? Give two examples of amphoteric oxides.
Answer:
Amphoteric oxides. The metal oxide which react both with acids as well as bases to produce salts and water are known as amphoteric oxides.

Examples. Zinc oxide, ZnO Aluminium oxide, Al2O3

Question 7.
Name two metals which will displace hydrogen from dilute acids, and two metals which will not.
Answer:
Zinc and magnesium can displace hydrogen from dilute acids. Copper and silver cannot displace hydrogen from dilute acids.

Question 8.
In the electrolytic refining a metal M, what would you take as the anode, the cathode and the electrolyte?
Answer:
During the electrorefining of metal, the impure metal is made as anode, a thin strip of pure metal M is made as cathode. The electrolyte used a soluble salt of metal M. to be refined.

Question 9.
Pratyush took sulphur powder on a spatula and heated it. He collected the gas evolved by inverting a test tube over it as shown in figure

Collection of Gas
(a) What will be the action of gas on
(i) dry litmus paper?
Answer:
No action.

(ii) moist litmus paper?
Answer:
It turns moist litmus paper red and then bleaches it.

(b) Write a balanced chemical equation for the reaction taking place.
Answer:
S + O₂ → SO₂

Question 10.
State two ways to prevent the rusting of iron.
Answer:
The rusting can be prevented by

1. By painting, oiling, greasing, galvanising, chrome plate or anodising.
2. By forming alloys.

Question 11.
What type of oxides are formed when non-metals combine with oxygen?
Answer:
As they form two types of oxides :
(a) Neutral oxides such as CO, NO etc.
(b) Acidic oxides such as SO₂, CO₂ etc.

Question 12.
Give reasons :
(a) Platinum, gold and silver are used to make jewellery.
Answer:
Platinum, gold and silver are used to make jewellery because these are not attacked by air and moisture. They don’t undergo corrosion and retain their lustre for a long time. Also these metals are malleable and ductile.

(b) Sodium, potassium and lithium are stored under oil.
Answer:
Sodium, potassium and lithium are stored under oil because in contact with moist air containing carbon dioxide, these are covered with a carbonate layer.
e.g. 4Na + O₂ → 2Na₂O
Na₂O + H₂O → 2NaOH
2NaOH + CO₂ → Na₂CO₃ + H₂O

Also they react with water.
e.g. 2Na + 2H₂O → 2NaOH + H₂.
Hence, these metals are stored under oil.

(c) Aluminium is a highly reactive metal, yet it is used to make utensils for cooking.
Answer:
This is due to the reason that a thin sticking oxide layer of aluminium is formed on its surface which prevents further reaction. Also aluminium is a good conductor of heat and the oxide layer (Al₂O₃) is stable even at high temperatures.

(d) Carbonate and sulphide ores are usually converted into oxides during the process of extraction.
Answer:
This is because it is easier to obtain a metal from its oxide as compared to its sulphide and carbonate ore.

Question 13.
You must have seen tarnished copper vessels being cleaned with lemon or tamarind juice. Explain why these sour substances are effective in cleaning the vessels.
Answer:
In tarnished copper vessel there is a layer of basic copper carbonate. This basic layer can be cleaned by using sour substances such as lemon or tamarind juice which are acidic in nature and dissolve the basic coat of copper carbonate

Question 14.
Differentiate betw een metals and non-metals.
Or
Differentiate between metals and non-metals on the basis of their chemical properties.
Answer:
Differences between metals and non-metals :

Question 15.
A man went door to door posing as a goldsmith. He promised to bring back the glitter of old and dull gold ornaments. An unsuspecting lady gave a set of gold bangles to him which he dipped in a particular solution. The bangles sparkled like new but their weight was reduced drastically. The lady was upset but after a futile argument the man beat a hasty retreat. Can you play the detective to find out the nature of the solution he had used?
Answer:
The solution used by goldsmith to bring back the glitter of old and dull gold ornaments was aqua regia. It is a freshly prepared mixture of cone. HCl and cone. HNOg in the ratio 3 : 1. It can dissolve gold,

Question 16.
Give the reasons why copper is used to make hot water tanks but steel (an alloy of iron) is not.
Answer:
This is because iron present in steel reacts with steam to form ferrosoferric oxide whereas copper has no action with water. As a result of it, the body of the steel tank becomes weaker and weaker in case of iron and not in case of copper.

Science Guide for Class 10 PSEB Metals and Non-metals InText Questions and Answers

Question 1.
Give an example of a metal which :
(i) is a liquid at room temperature
Answer:
Mercury

(ii) can be easily cut with a knife
Answer:
Sodium

(iii) it is the best conductor of heat
Answer:
Silver

(iv) is a poor conductor of heat.
Answer:
Lead.

Question 2.
Explain the meaning of malleable and ductile.
Answer:
Malleable: A substance is said to be malleable, if it can be beaten into sheets. e.g. metals are malleable.
Ductile: A substance is said to be ductile, if it can be drawn into wires e.g. the metals are ductile.

Question 3.
Why is sodium kept immersed in kerosene oil?
Answer:
This is because in contact with moist air containing carbon dioxide, it is covered with a carbonate layer.
4Na + O₂ → 2Na₂O
Na₂O + H₂O → 2NaOH
2NaOH + CO₂ → Na₂CO₃ + H₂O

Also sodium reacts with water.
2Na + 2H₂O → 2NaOH + H₂
Hence, sodium is kept immersed in kerosene oil.

Question 4.
Write equation for the reactions of
(i) iron with steam
Answer:

(ii) calcium and potassium with water.
Answer:
Ca + 2H₂O → Ca(OH)₂ + H₂
2K + 2H₂O → 2KOH + H₂

Question 5.
Samples of four metals A, B, C and D were taken and added to the following solution one by one. The results obtained have been tabulated as follows :

Use the table above to answer the following questions about metals, A, B, C and D.
(i) Which is the most reactive metal?
Answer:
B is the most reactive metal.

(ii) What would you observe if B is added to a solution of copper (II) sulphate?
Answer:
B will displace copper from copper sulphate solution.

(iii) Arrange the metals A, B, C and D in the order of decreasing reactivity.
Answer:
The decreasing order of reactivity is B > A > C > D.

Question 6.
Which gas is produced when dilute hydrochloric acid is added to a reactive metal? Write the chemical reaction when iron reacts with dilute H₂SO₄.
Answer:
Hydrogen gas is produced when dilute hydrochloric acid is added to a reactive metal.

Question 7.
What would you observe when zinc is added to a solution of iron (II) sulphate? Write the chemical reaction that takes place.
Answer:
When zinc is added to a solution of iron (II) sulphate it will displace iron from it and light green colour of solution gradually fades away.

Question 8.
(i) Write the electron-dot structures for sodium, oxygen and magnesium.
Answer:
Electron-dot structures for sodium, oxygen and magnesium are

(ii) Show the formation of Na₂O and MgO by the transfer of electrons.
Answer:
Formation of Na₂O:

(iii) What are the ions present in the above compounds?
Answer:

Question 9.
Why do ionic compounds have high melting points?
Answer:
In ionic compounds there are strong electrostatic forces of attraction between oppositely charged ion and a considerable amount of energy is required to break the strong interionic attraction.

Question 10.
Define the terms :
(a) mineral
Answer:
Mineral. The compounds of elements occurring in earth’s crust which are associated with earthly impurities are called minerals.

(b) ore
Answer:
Ore. An ore is a mineral from which metal can be extracted conveniently and economically.

(c) gangue.
Answer
Gangue. The earthly impurities such as sand, lime stone, rocks etc. associated with minerals and ores are collectively known as gangue or matrix.

Question 11.
Name two metals which are found in nature in the free state.
Answer:
Gold and Platinum.

Question 12.
What chemical process is used for obtaining a metal from its oxide?
Answer:
Reduction process.

Question 13.
Metallic oxides of zinc, magnesium and copper were heated with the following metals :

In which cases will you find displacement reactions taking place?
Answer:
Zinc can displace copper from copper oxide

Magnesium can displace zinc from zinc oxide

Also Mg can displace copper from CuO

Question 14.
Which metals do not corrode easily?
Answer:
The metals which are not attacked by air and moisture don’t corrode easily.

Question 15.
What are alloys?
Answer:
Alloys. These are the homogeneous mixtures of two or more metals or metals and non-metals.

Punjab State Board PSEB 10th Class Agriculture Book Solutions Chapter 7 Contribution of Agriculture in Economic Development Textbook Exercise Questions and Answers.

PSEB Solutions for Class 10 Agriculture Chapter 7 Contribution of Agriculture in Economic Development

Agriculture Guide for Class 10 PSEB Contribution of Agriculture in Economic Development Textbook Questions and Answers

(A) Answer in one-two words:

Question 1.
How much population of our country lives in villages?
Answer:
More than two-third.

Question 2.
What proportion of labour force in India is dependent directly on agriculture?
Answer:
54%.

Question 3.
What is the contribution of agriculture in gross domestic product in the country?
Answer:
According to 2012-13 data it was 13.7%.

Question 4.
How much food grains were produced in 1950-51 and how much did it increase to in 2013-14?
Answer:
It was 51 million ton in 1950-51, which was 264 million ton in 2013-14.

Question 5.
Which are the three sectors of Indian economy?
Answer:
Agriculture, Industry and service sector.

Question 6.
Where does India stand in foreign trade?
Answer:
Tenth.

Question 7.
Which country has been left behind by India in the field of rice export?
Answer:
Thailand.

Question 8.
Name the major industries dependent for raft material on agriculture.
Answer:
Textile industry, sugar industry, jute industry.

Question 9.
In which year the Food Security Act was passed?
Answer:
In the year 2013.

Question 10.
What is India’s agricultural balance of trade?
Answer:
According to 2013-14, balance of trade was surplus by 25 billion dollar.

(B) Answer in one-two sentences:

Question 1.
How agricultural development is linked with dependence of population on agriculture?
Answer:
Dependence of people on agriculture helps in good growth and development of economy. As the economy of country develops, dependence on agriculture automatically decreases.

Question 2.
What are the main agricultural exports of India?
Answer:
Cotton, pulses, oil, fruits, tea, coffee, vegetables, cashew, spices, rice, wheat etc.

Question 3.
What are the main agricultural imports of India?
Answer:
Pulses, oil seed, dry fruits, edible oil etc.

Question 4.
Name a few agricultural based enterprises. Or Write the name of any four agriculture based enterprises.
Answer:
Dairy farming, poultry farming, fish farming, piggry, animal husbandry, fish farming, agroforestry etc. are some agricultural based enterprises.

Question 5.
Why a buffer stock of food grains in the country is maintained?
Answer:
This is done to control the rise in prices in case of inflation in future under the fear of fall in supply. Needy families are provided with foodgrains every month from this stock under Public Distribution System (PDS).

Question 6.
What are the main provisions of Food Security Act, passed by Govt of India in year 2013?
Answer:
The main provisions of the food security act is to provide 5 kg of grains per kg per month to 75% rural population and to 25% urban population.

Question 7.
How development of railways is linked to the agricultural development?
Answer:
Railways are used to transport agricultural produce from one part of the country to other parts of country and this way department of railways get income and this helps in the expansion and development of railways.

Question 8.
Name the industries which depend upon agriculture for marketing of their products. Or Write name of four agro-based industries.
Answer:
Tractor, agricultural implements, fertilizers, weedicides, insecticides etc. are used in agricultural sector. Those industries which manufacture them or produce them depend on agriculture sector for marketing these products.

Question 9.
What type of unemployment do we find in agriculture?
Answer:
Unemployment found in agriculture sector is seasonal and .hidden or disguised unemployment.

Question 10.
What are the benefits of allied activities of agriculture?
Answer:
Allied activities of agriculture are helpful to farmers in the sense these fulfil their daily needs by providing them with better and nutritious diet and also as source of extra income, e.g. milk, eggs, meat, fish, honey etc. are the products which they obtained from these allied activity, consume market and sell these and this helps in adding to their income also.

(C) Answer in five-six sentences

Question 1.
What is the contribution of agriculture in economic development of India?
Answer:
Nearly two-third population of our country depends on agriculture and 54% of the labour force directly depend on agriculture. GDP of the nation from agriculture was 13.7% in the year 2012-13. Several industries are based on agriculture e.g. sugar, jute and textile industries. Products from many industries are used in agriculture.

Transportation, godowns, warehouses add to the economy of the country. Several agricultural products are exported and country gain in terms of dollars. Due to export of agricultural products central government gain from export duty. State government earns from land taxes and also from irrigation. Marketing fees also adds to the government treasury. Agriculture adds to the economy of the country.

Question 2.
What is the significance of agriculture in India’s foreign trade?
Answer:
Foreign trade of India is very deeply dependent on agriculture. Several agriculture products are imported e.g. tea, coffee, spices, oil, cotton, fruits, vegetables, pulses, cashew and now wheat and rice,also. In 2012, India was at the top in the export of rice by leaving behind-Thailand. India is at 10th place in export of grains in the world. Some materials like cotton fibre, yam, readymade cloth, jute products etc. are also exported. In year 2013-14 gross export of agricultural products was 42 billion dollar and in the same year import was of 17 billion dollar. This way India’s balance of trade was surplus by 25 billion dollar.

Question 3.
What were the main reasons of Green Revolution in the country?
Answer:
After the independence of India, for many decades we remained dependent on other countries for grain. Hard work of farmers of India, researched by scientists, improved seeds, agricultural implements, fertilizers, pesticides etc. helped in bringing green revolution. Grain production became so large that now we export wheat, rice and other agricultural products.

Question 4.
Why the pressure on agriculture should be reduced in India? Give reasons.
Answer:
Large proportion of our population depends on agriculture. Nearly 54% of labour force is directly engaged in agriculture sector. An economy can develop and grow in a better way if we can reduce our dependence on agriculture. Seasonal and hidden unemployment is found in agricultural sector it is necessary to provide some other jobs to such workers. As the economy of the country grows, dependence on agriculture decreases automatically and dependence on industry and services sector increases.

Question 5.
How does agricultural and industrial growth depend on each other?
Answer:
If agriculture develops and grows in a country, then various types I of agriculture produces are available in large quantities. There is need to establish various industries for the processing and consumption of these produces. Some parts of our country where these products are not available, these are transported to such parts of the country. The excess grains are stored in warehouses.

Some of the industries based on agriculture are sugar industry, jute industry, shellar, oil extracting industry etc. This way agriculture development helps in the growth of industry. But for sustained agricultural development, some other products and implements etc. are needed in the agriculture sector. Products from various industries e.g. tractor industry, machinery, fertilizers, pesticide and other chemicals etc. are used in agriculture sector. This way industrial development is related to agriculture development.

PSEB 10th Class Agriculture Guide Contribution of Agriculture in Economic Development Important Questions and Answers

Multiple Choice Questions

Question 1.
During the year 2012-13, share for GDP from agriculture sector was:
(a) 13.7%
(b) 15.9%
(c) 11.5%
(d) None.
Answer:
(a) 13.7%

Question 2.
Grain production in India during 2013-14 was:
(a) 264 million ton
(b) 51 million ton
(c) 100 million ton
(d) None.
Answer:
(a) 264 million ton

Question 3.
Main agricultural exports of India:
(a) tea
(b) cotton
(c) pulses
(d) All.
Answer:
(d) All.

Question 4.
Which country has been left behind by the India in the field of rice export?
(a) Thailand
(b) Bhutan
(c) America
(d) Sri Lanka.
Answer:
(a) Thailand

Question 5.
In 2012 buffer stock of food grain was-
(a) 82 million ton
(b) 25 million ton
(c) 52 million ton
(d) 108 million ton
Answer:
(a) 82 million ton

Question 6.
Under provision of Food Security Act-2013, how much grain to be alloted per person per month?
(a) 5 kg
(b) 10 kg
(c) 15 kg
(d) 20 kg.
Answer:
(a) 5 kg

True or False:

1. Many industries get, their raw material from agriculture.
Answer:
True

2. In the year 2012, India got first position in the export of rice leaving behind Thailand.
Answer:
True

3. There is seasonal and disguised unemployment in the field of agriculture.
Answer:
True

4. India’s gross agricultural exports stood at 42 billion dollar in 2013-14.
Answer:
True

5. The yield of food grains increased to about 2125 kg per hectare.
Answer:
True.

Fill in the blanks:

1 is considered to be back bone of Indian economy.
Answer:
Agriculture

2. India is now placed at number in import of agricultural produce and food grains in the world.
Answer:
Ten

3. In the year 2012, our country had a buffer stock of tones of food grains.
Answer:
82 million

4. About of the households are engaged in dairy farming in India.
Answer:
70 million.

Very Short Answer Type Questions

Question 1.
What is agriculture for our country?
Answer:
Back bone of our economy.

Question 2.
How much population is involved in the occupation for dairy farming in our country?
Answer:
70 million families.

Question 3.
Which of the sectors come under the service sectors?
Answer:
Banking services, transportation, storage and warehouses, insurance, tourism etc.

Question 4.
What is the place of our country in the world on the basis of population?
Answer:
2nd place.

Question 5.
How much percentage in household consumption is from agriculture?
Answer:
60%.

Question 6.
What is the yield of grains?
Answer:
2125 kg per hectare.

Question 7.
How much was the stock of grains in the country in the year 2012?
Answer:
82 million tons.

Question 8.
How much wheat would be supplied at a subsidized rate to feed to 82 crores of population every year?
Answer:
61 million ton.

Question 9.
In export of which agriculture product India remained at top in year 2012?
Answer:
Rice.

Question 10.
How much was the total agricultural export in the year 2013-14?
Answer:
42 billion dollar.

Question 11.
How many percent of workers in India are directly engaged in agriculture?
Answer:
50% workers.

Short Answer Type Questions

Question 1.
Which are the small scale industries based on agriculture?
Answer:
Small scale industries based on agriculture are-rice shellar, oil extraction etc.

Question 2.
Which is the third sector of economy? Give example.
Answer:
Third sector is service sector in economy, e.g. Banking services, transportation, warehouses, insurance sector, tourism etc.

Long Answer Type Questions

Question 1.
Country has become self-dependent in the production of grains. Explain by comparison.
Answer:
In the year 1950-51, food grain production was 51 million ton which in the year 2013-14 became 264 million tons. Grain yield has also increased and is approximately 2125 kg per hectare. In the year 2012 country had 82 million ton of food grains in the buffer stock which itself is a record. This shows that country has become self-dependent.

Question 2.
Write any five reasons for the green revolution in the country?
Answer:

• Increased availability and ease of sources of irrigation.
• The use of fertilizers helped in obtaining higher yields.
• Discovery and use of high-yielding varieties.
• Protection of crops against diseases, weeds, and insects became easy.
• Increased use of Agri machinery.

Question 3.
Write any four reasons for the green revolution in India.
Answer:
Do yourself.

Punjab State Board PSEB 10th Class Agriculture Book Solutions Chapter 6 Agroforestry Textbook Exercise Questions and Answers.

PSEB Solutions for Class 10 Agriculture Chapter 6 Agroforestry

Agriculture Guide for Class 10 PSEB Agroforestry Textbook Questions and Answers

(A) Answer in one-two words:

Question 1.
How much area should under forests in Punjab, as per National Forest Policy 1988?
Answer:
20%.

Question 2.
How much area is under forests and tree cover in Punjab?
Answer:
6.49%.

Question 3.
How many major agro climatic zones are there in Punjab on the basis of climate?
Answer:
Three.

Question 4.
In which season acute shortage of fodder is felt in Kandi region of Punjab?
Answer:
In winter.

Question 5.
What is the spacing for planting of poplar on boundary of a field?
Answer:
3 metres.

Question 6.
What types of .soils are there in Kandi region?
Answer:
Soil is undulating that is not uniformly levelled. It has many ups and down.

Question 7.
Name two trees used for fodder in Kandi region.
Answer:
Dhak, Beri, Chhal, Kachnar etc.

Question 8.
What should be the pH of soil for poplar cultivation?
Answer:
6.5 to 8.0.

Question 9.
Name the trees suitable for commercial agroforestry in Punjab.
Answer:
Poplar, Eucalyptus

Question 10.
How many Poplar plants are planted in per hectare?
Answer:
200 trees per acre.

(B) Answer in one-two sentences:

Question 1.
What is the planting time of Poplar in Punjab?
Answer:
Suitable time for planting poplar in Punjab is January-February.

Question 2.
Define Agroforestry.
Answer:
Agroforestry is a land management system in which cultivation of trees and crops is done together in a field along with rearing of animals on the same piece of land.

Question 3.
What type of soil and irrigation facilities are available in Central plain zone in Punjab?
Answer:
In this zone, soil is fertile and irrigation facilities are available here.

Question 4.
What type of trees are found in S-W region of Punjab?
Answer:
Kikar, Tahli, Mango, Dhrek, Nim, Jamun, Toot etc. trees are planted in south-western zone.

Question 5.
Write down planting and spacing requirements of Eucalyptus.
Answer:
Cuttings are used for the propagation of Eucalyptus. Eucalyptus can be planted on the boundaries of the field or in block plantation. Plant to plant spacing on the boundaries should be 2 metres and if planted in block plantation the spacing should be 4 x 2 m.

Question 6.
Write the clones of poplar planted in Punjab.
Answer:
PL-1, PL-2, PL-3, PL-4, PL-5, L-47/88, L-48/89 are clones of poplar.

Question 7.
What is the planting time of Eucalyptus in Punjab?
Answer:
Eucalyptus can be planted in March-April and July-August.

Question 8.
Write down the names of the industries where poplar wood is used.
Answer:
Wood obtained from poplar can be used in Match box industry, ply manufacturing, packing cases etc.

Question 9.
What is the spacing for poplar planting?
Answer:
If poplar is planted on boundaries then plant spacing should be 3 metre and if it is planted in die whole field then spacing should be 8 x 2.5 m or 5 x4m.

Question 10.
Write the name of trees grown in Kandi region.
Answer:
Toot, Nim, Tahli, khair, Kikkar, Bel, Kachnar, Mango, Subabaul, Aijun, Harar, Behra, Phalis and dhak, Dehrek, Sohanjana etc.

(C) Answer in Jive-six sentences:

Question 1.
Write down the clones planted and spacing for poplar planting in Punjab. .
Answer:
PL-1, PL-2, PL-3, PL-4, PL-5, L-47/88, L^18/89 are some of the clones of poplar. If poplar is planted on boundaries then plant spacing should be 3 metre and if it in planted is the whole field then spacing should be 8 x 2.5 m or 5 x 4 m. 200 plants per acre can be planted in the field.

Question 2.
Write down the source of clonal Eucalyptus plants in Punjab.
Answer:
We should plant Eucalyptus plants prepared from cuttings in Agroforestry. These all grow uniformely. These can be obtained from any nursery of department of forests and wildlife preservation, Punjab, PAU, Ludhiana or any other private registered nursery.

Question 3.
How poplar can be planted?
Answer:
Make a pit which is 3 feet deep and have diameter of 15-20 cm. Use chloropyriphos and Emisan-6 against termies and diseases. Plant poplar trees in the month of January and February. Water the plants immediately after planting the poplar tree. If poplar is planted on boundaries then plants spacing should be 3 metre and if it in planted in the whole field then spacing should be 8 x 2.5 m or 5 x 4 m. 200 plants per acre can be planted in the fields.

Question 4.
Where poplar wood is used?
Answer:
Cultivation of poplar is helpful in creating employment and also in small enterprises in which wood is the raw-material. Poplar is used in various industries e.g. it is used in the manufacturing of match sticks. It is also used in the manufacture of plywood and also in the packaging industry to make boxes. This way one can earn by the cultivation of poplar. It sheds off its leaves in winter thus has no harm for Rabi crops.

Question 5.
Why Poplar and Eucalyptus are suitable for commercial Agroforestry? Or Why are Eucalyptus and poplar cultivated as commercial agro forestry in Punjab?
Answer:
Poplar and Eudalyptus are suitable for commercial agroforestry in Punjab. Wood obtained from these trees can be easily marketed. The income from these trees in more than wheat-rice cropping system.

Safeda:
It grows in less time, stem is straight, its branches shed off regularly. Its wood is used as building material, its pulp is used in paper industry, wooden beams are also obtained from it. Therefore it is suitable for cultivation in agroforestry.

Poplar:
It provides employement. Its wood is used in small scale industry; like, ply, match sticks, packing boxes etc. It also does not affect the Rabi crops.

PSEB 10th Class Agriculture Guide Agroforestry Important Questions and Answers

Multiple Choice Questions

Question 1.
According to National Forest Policy 1988, forests should occupy of area in plain states.
(a) 5%
(b) 20%
(c) 50%
(d) 29%.
Answer:
(b) 20%

Question 2.
In central plain region trees are grown.
(a) Poplar
(b) Dek
(c) Eucalyptus
(d) All
Answer:
(d) All

Question 3.
………….. is not a variety of poplar:
(a) PL-5
(b) PL-47/88
(c) PL-858
(d) PL-48/89.
Answer:
(b) PL-47/88

Question 4.
Poplar trees become ready in years for harvesting.
(a) 5 to 7
(b) 1 to 2
(c) 10 to 12
(d) 15 to 25.
Answer:
(a) 5 to 7

Question 5.
pH value for soil for poplar cultivation.
(a) 10
(b) 6.5 to 8.0
(c) 3 to 4
(d) 4 to 5.5.
Answer:
(b) 6.5 to 8.0

Question 6.
In which direction the trees are planted on ridges of the farms for agro forestry?
(a) North-South
(b) East-west
(c) South-east
(d) North-east.
Answer:
(a) North-South

Question 7.
For timber production after how many years Eucalyptus can be harvested?
(a) 13 to 15 years
(b) 6 to 8 years
(c) 4 to 6 years
(d) 2 to 4 years.
Answer:
(a) 13 to 15 years

Question 8.
For batten production, after how many years Eucalyptus can be harvested?
(a) 13 to 15 years
(b) 6 to 8 years
(c) 4 to 6 years
(d) 2 to 4 years.
Answer:
(c) 4 to 6 years

Question 9.
For paper pulp production, after how many years Eucalyptus can be harvested?
(a) 13 to 15 years
(b) 6 to 8 years
(c) 4 to 6 years
(d) 2 to 4 years.
Answer:
(b) 6 to 8 years

True False:

1. Poplar is more successful in Bet area.
Answer:
True

2. Poplar tree become ready for harvesting after 5-7 years.
Answer:
True

3. To save orchards from wild life, Jatropha are grown around the orchards.
Answer:
True

4. Poplar cultivation is successful in Kallar and water logged soils.
Answer:
False

5. Eucalyptus clonal plants should be planted in Agroforestry.
Answer:
False

Fill in the blanks:

1. Poplar wood is used in the manufacture of ……………. .
Answer:
Match sticks

2. For boundaries poplar trees are planted at spacing.
Answer:
3 m

3. …………….. erosion is major problem in sub-mountainous zone.
Answer:
Soil

4. Pl-3 is a …………….. clone.
Answer:
poplar

5. In winter the scarcity of ……………. is felt in submountaneous zone.
Answer:
fodder.

Very Short Answer Type Questions

Question 1.
Why is agroforestry suitable for Punjab?
Answer:
It helps in increasing the area under the forests and trees.

Question 2.
Can we take income from agroforestry?
Answer:
Yes, more than the conventional agricultural practices i.e. more than paddy-wheat cropping system.

Question 3.
In which direction, trees should be planted on the boundaries of fields? (PS.E.B. 2017)
Answer:
In North-South direction.

Question 4.
In how many zones is Punjab divided on the basis of climate?
Answer:
Three zones.

Question 5.
On what basis the farmer in Kandi area grow their crops?
Answer:
Agriculture is based on the rainfall.

Question 6.
Which of the trees are planted to save the orchards?
Answer:
Jatroffa, Karonda, Ipomea.

Question 7.
What type of soil is found in south-western zone?
Answer:
Saline and alkaline soil.

Question 8.
Poplar is not harmful for rabi crops, how?
Answer:
Its leaves shed off in winter and it is not harmful for rabi crops.

Question 9.
What type of soil is not suitable for poplar?
Answer:
Kallar and water-logged.

Question 10.
In which area poplar is must successful?
Answer:
In bet area.

Question 11.
How many poplar trees can be planted in the field?
Answer:
200 trees per acre.

Question 12.
In how many years poplar trees are ready?
Answer:
5 to 7 years.

Question 13.
What type of Eucalyptus plants should be planted?
Answer:
Prepared from cuttings.

Question 14.
How many Eucalyptus plants are planted In the whole field?
Answer:
500 trees per acre.

Question 15.
If Eucalyptus cultivation is for long time, what should be row spacing?
Answer:
8 metre.

Question 16.
After how many years can we get wood for buildings (timber) from Eucalyptus?
Answer:
13 to 15 years.

Question 17.
After how many years is Eucalyptus ready for pulp?
Answer:
6 to 8 years.

Question 18.
After how many years Eucalyptus is ready for battens?
Answer:
4 to 6 years.

Question 19.
Write file name of two trees which are mainly grown in Punjab for commercial agroforestry.
Answer:
Poplar, Eucatyplus.

Short Answer Type Questions

Question 1.
Write the name bf two main models for agroforestry?
Answer:
There are two main models for agroforestry-Boundary plantation and intercropping in block plantation.

Question 2.
Where do farmers plant trees if they use boundary plantation model?
Answer:
They plant trees on the boundaries of fields.

Question 3.
Which of the trees are used for planting on the boundaries?
Answer:
Subabaul, Drek, Toot, Eucalyptus, Poplar, Siris, Lassora, Sohanjana, Nim, Tahli etc. –

Question 4.
Which farmers do the mixed farming of crops and trees?
Answer:
Those farmers who have more agricultural land can do mixed farming.

Question 5.
Which of the trees are suitable for planting in the whole field?
Answer:
Poplar, Eucalyptus, Dhrek and Tun are suitable trees.

Question 6.
In which area is the problem of soil erosion found?
Answer:
Soil found in the Kandi area is not uniform and land has many ups and downs (undulating) therefore problem of soil erosion is also found there.

Question 7.
Which type of soil is suitable for poplar?
Answer:
Well drained, loamy to sandy, fertile soil and which have pH value from 6.5 to 8.0 is suitable for growing popular.

Question 8.
List four uses of wood of Eucalyptus.
Answer:
Batten, pulp, wood used in buildings construction, industry, furniture

Question 9.
Write the name of four trees which are grown in whole field in agroforestry.
Answer:
Poplar, Eucalyptus, Toon, Dhrek.

Question 10.
Why salinity is found in the upper surface of the soil in the South-Western zone?
Answer:
Water under the earth in this zone is saline. This makes upper surface of the soil also saline.

Long Answer Type Questions

Question 1.
Write about trimming and pruning of poplar? Or Write the benefit of correctly pruning poplar plants at the right time.
Answer:
There is no need of trimming in the first year, but in the second year after shedding off the leaves there is a need of pruning of the trees to make it straight and to give it good appearance. If trimming and pruning is done at proper time then the stem remains straight and without nodes.

Question 2.
Which of the qualities of Eucalyptus make it suitable for cultivation in agroforestry? Or For which qualities Eucalyptus is grown in agroforestry?
Answer:
It grows in less time, stem is straight, its branches shed off regularly. Its wood is used as building material, its pulp i§, used in paper industry, wooden beams are also obtained from it. Therefore it is suitable for cultivation in agroforestry.

Question 3.
Define Agroforestry.
Answer:
According to National Forest Policy 1988, to fulfil the needs based on wood and to keep the environment safe, area under the forests should be 20%. But it is not possible to increase the area under the forests therefore this is achieved by agroforestry. Agroforestry is the cultivation of trees and crops together in the same field. The objective behind this, type of cultivation is that farmers can fulfil their needs e.g. cereals, wood, fuel, fodder and also can save the natural resources e.g. soil, water, air etc. There is also an increase in their income.

Question 4.
What do you mean by agroforestry? Explain in detail about the planting trees on farm boundaries in agroforestry.
Answer:
Do it yourself.

Punjab State Board PSEB 10th Class Science Important Questions Chapter 2 Acids, Bases and Salts Important Questions and Answers.

PSEB 10th Class Science Important Questions Chapter 2 Acids, Bases and Salts

Long Answer Type Questions

Question 1.
What do you mean by neutralization reaction? Explain with an experiment.
Answer:
It is a chemical reaction in which acids reacts with base to form salt and water. It is known as neutralization reaction.

Process of neutralization

Experiment: Take a solution of dilute sodium hydroxide in a beaker. Add few drops of phenolphthalein in this solution. Its colour changes to pink. Take a burette filled with dilute hydrochloric acid. Fix it vertically on a stand as shown in Fig. Place a beaker under it. Add the hydrochloric acid slowly to the beaker with the help of burette and go on swirling the beaker slowly. When the colour of solution disappears then stop adding acid to beaker. Now there is no effect of Red to Blue litmus to the solution. Now there is only salt and water in the beaker which is neutral to litmus. This is known as neutralization reaction.

Example:
HCl + NaOH → NaCl + H₂O
Cu(OH)₂ + H₂SO₄ → CuSO₄ + H₂O
HCl + KOH → KCl + H₂O

Question 2.
Write briefly chemical properties of acids.
Answer:
Acids have several chemical properties :
1. Reaction with metals. Acids reacts with active metals. Zinc, Magnesium, Iron, Mangenese etc. reacts with them to produce hydrogen gas.
Zn(s) + dil. H₂SO₄(aq) → ZnSO₄(aq) + H₂(g)
Mg(s) +dil.2HCl(aq) → MgCl2(aq) + H₂(g)
Fe(s) + dil. H₂SO₄ (aq) → FeSO4(aq) + H₂(g)
Mn(s) + dil. HNO₃ (aq) → Mn(NO₃)(aq) + H₂ (g)

2. Reaction with metals carbonate and metal bicarbonate. Acids reacts with metal carbonate and metal bicarbonate to produce C02.
Na₂CO₃ + H₂SO₄ → Na₂SO4 + H₂O + CO₂
NaHCO₃ + HCl → NaCl + H₂O + CO₂
CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂
K₂CO₃ + 2HCl → 2KCl + H₂O + CO₂

3. Reaction with bases. Acids reacts with base to show neutralization. They produce salt.
HCl + NaOH → NaCl + H₂O
HCl + KOH → KCl + H₂O
Cu(OH)₂ + H₂SO₄ → CuSO₄ + H₂O

4. Reaction with sulphites and bisulphites. Acids react with metal sulphite and bisulphite to produce SO₂ gas.
CaSO₃ + H₂SO₄ → CaSO₄ + H₂O +SO₂ (g)
NaHSO₃ + HCl → NaCl + H₂O + SO₂(g)

5. Reaction with metal sulphides and hydrogen sulphides. Acids react with metal various metal sulphide and hydrogen sulphides to produce H₂S gas.
FeS + H₂SO₄ → FeSO₄ + H₂ S(g)

6. Reaction with metal Chlorides. When metal chloride heated with acids the reaction takes place.
NaCl + H₂SO₄ → NaHSO₄ + HCl (g)
NaCl + NaHSO₄ → Na₂SO₄ + HCl (g)

7. Reaction with metal nitrates. Concentration acid reacts with metal nitrate.
NaNO₃ +H₂SO₄ → NaHSO₄ + HNO₃
NaNO₃ + NaHSO₄ → Na₂SO₄ + HNO₃

8. Reaction with metal oxides. Metal oxides reacts with dilute acids to form salts of
Na₂O + 2HNO₃ → 2NaHO₃ + H₂O
CuO + 2HCl → CuCl₂ + H₂O

Question 3.
Write in brief chemical properties of bases/alkalis.
Answer:
Important chemical properties of bases/alkalis are given below :
1. Reaction with metals, Bases react with some metals to produce hydrogen gas.

2. Reaction with air. Some bases react with CO₂ present in air.
2NaOH + CO₂ → Na₂CO₃
2KOH + CO₂ → K₂CO₃

3. Reaction with acids. Bases react with acids to produce salts.
NaOH+ HCl → NaCl + H₂O
Fe(OH)₂ + 2HCl → FeCl₂ + 2H₂O
Ca(OH)₂ + 2HCl → CaCl₂ + 2H₂O

4. Reaction with salts. Salts of copper, iron, Zinc etc. react with bases and produce insoluble metal hydroxides.
ZnSO₄ + 2NaOH → Na₂SO₄ + Zn(OH)₂ ↓
CuSO₄ + 2NH₄OH → (NH₄)₂SO₄ + Cu(OH)₂ ↓
FeCl₃ + 3NaOH → 3NaCl + Fe(OH)₃ ↓

Question 4.
What is the importance of pH in everyday life?
Answer:
pH has very important role in our life :
1. In animal world. Many of the processes in our body occur within the pH range of 7-0 to 7-8. We can survive only in this narrow range. pH value of our blood, tears, saliva is nearly 7-4. Survival will become impossible if this value becomes less than 7-0 or more than 7-8. When pH of rain water decreases from 7-0 to 5-6 or less then it is called acid rain. WThen acid rain flows to the rivers then pH value of river water lowers. Survival of aquatic life in such rivers become difficult.

2. For plants. For healthy growth of plants a specific pH range of soil is required. If soil becomes more basic or acidic, produce badly affected.

3. Digestive system. Our stomach produces HCl, which without harming us help in the digestion of food. Duiing indigestion the stomach produces too much of acid. This causes pain and irritation in the stomach. To get rid of this pain, bases are used which are called antacids. For this weak base like milk of magnesia is used.

4. Tooth decay. If pH value of the mouth is lower than 5-5, then tooth decay begins. Our teeth are made up of calcium phosphate which is hardest substance in our body. It is not soluble in water but starts decaying when pH of the mouth is lower than 5-5. Bacteria present in the mouth produce acids by .degradation of sugar and food particles. To get rid of this we should use basic tooth paste. This will neutralize the acid and tooth decay can be prevented.

5. Relief from insect stings. When some insects sting us, they leave a special type of acid in our body. Bees, ants etc. leave methanoic acid in our body by their sting. To get relief from pain, mild base like baking soda is rubbed on the stung area.

6. Safety from special plants. Plants like nettle have stingging hair. By touching them we feel pain similar to insect sting. This pain is due to methanoic acid. Conventionally, one can get relief by rubbing leaves of dock plant on the stung area.

Short Answer Type Questions

Question 1.
What are indicators? How do indicators are categorized? Explain.
Answer:
Those substances which change their colour in acidic and basic solutions, are called indicators.
Indicators are categorized into two types on the basis of their special properties and characteristics.

1. Indicators which give colour to acids and basic medium.
2. Indicators which give smell to acids and basic medium.

1. Colour giving indicators :
(A) Litmus solution: Litmus solution is purple dye which is obtained from Lichen plant. This is available as red or blue solution and also in the form of litmus paper. Blue litmus turn to red in the presence of acids and Red litmus turns to blue in the presence of basic media. Litmus is neither acidic nor basic by itself.

(B) Turmeric: Turmeric change to red-brown colour in the presence of bases. That is why vegetable stain on the clothes becomes red brown when washed by applying soap which is alkaline.

(C) Phenolphthalein: This is synthetic indicator. It gives pink colour in the presence of bases.

(D) Methyl orange: This is also synthetic indicator. It gives pink colour in the presence of acidic medium and yellow in the presence of bases.

2. Olfactory indicators: Chopped onion, vanilla essence and clove oil change smell in the presence of acids and bases act as olfactory indicators.

Question 2.
What is dilution?
Answer:
When we mix an acid or base with water, the number of H+/OH~ ions per unit volume decreases, it is called dilution. By dilution, acids and bases are ionized.

Question 3.
Give characteristics of acids.
Answer:

• They are sour to taste.
• They turn blue litmus to red.
• Their solution is not like soap solution.
• They produce hydrogen gas when reacts with metals.
• They react with carbonates to produce carbon dioxide.
• Acid react with bases to produce salts and water.

Question 4.
Give four uses of acids in our everyday life.
Answer:

1. Vinegar is used in cooking food and acts as preservative and used in pickles.
2. HCl in our stomach destroys the harmful bacteria, which reach there with our food.
3. Tartaric acid is used to prepare baking soda.
4. Carbonic acid is used in soft drinks.

Question 5.
What are the harmful effects of acids in everyday life?
Answer:

• They can destroy living cells.
• Concentrated acids can badly damage the skin and soft organs.
• These can damage eatables.

Question 6.
Differentiate between strong acids and weak acids.
Answer:

Question 7.
Differentiate between strong base and weak base.
Answer:

Question 8.
Categorize the following compounds as strong and weak acids and bases,
(i) HCl
(ii) H₂SO₄
(iii) CH₃CHOOH
(iv) HCN
(v) NH₄OH
(vi) H₃PO₄
(vii) NaOH
(viii) Ca(OH)₂
(ix) KOH
(x) H₂CO₃
Answer:

Question 9.
What is the reason for electric conduction in acids? Explain.
Answer:
Acids produce H+ ions. Due to ions acids can conduct electricity. This conduction takes place in water solution.
HCl + H₂O → H₃O + +Cl^–
HNO₃ +H₂O → H₃O+ +NO₃^–

Question 10.
What happens when a base is dissolved in water? Explain it.
Answer:
Bases when dissolved in water give hydroxide OH^– ion. The water-soluble bases are called alkalis.

Question 11.
Why are bases not touched or tasted?
Answer:
Bases have a bitter taste like soaps and are harmful to skin. They are harmful when touched or tasted.

Question 12.
Write uses of alkalies/bases.
Answer:

• These are used to make soap.
• These are used in basic batteries.
• These are used in making antacids.
• Used in Petrol refining and paper industry.
• To remove stains of grease from cloths.
• To make hard water, soft.

Question 13.
Give normal characteristics of bases.
Answer:

• They are bitter to taste.
• They are soapy to touch and are harmful for skin.
• These turn litmus to blue.
• These turn turmeric to red brown colour.
• These react with acids to produce salts and water.
• They turn phenolphthalein solution to pink.

Question 14.
What is difference between alkali and base?
Answer:
Those alkalies which are soluble in water are called bases. This means all bases are alkalies but all alkalies are not bases, e.g. Ferric hydroxide [Fe(OH)3] and cupric hydroxide [Cu(OH)2] are alkalies but are not bases since these are not soluble in water.

Question 15.
What are the sources to get common salt (NaCl)? Explain.
Answer:
We can get common salt from following sources :

• Sea water: A huge amount of salt is dissolved in sea water. Salt in obtained from sea water through salt shallows. Solar heat and air help in the evaporation of sea water. We get salt.
• Mineral salt: Deposits of solid salt are found in many parts of the world. These beds of rock salts were formed when seas of bygone ages dried up. This salt is mined similar to the mining of coal. These rocks are found in Mandi (Himachal Pradesh), Khewra (Pakistan). Due to impurities this salt is brown in colour.
• From Lakes: Salt is obtained from Sambher lake in Rajasthan, great salt lake in America, Lake Elton in Roose etc. This salt in obtained by evaporation.

Question 16.
Write characteristics of common salt.
Answer:

• Colour and state: It is colourless crystalline substance which melts at 820°C.
• Solubility: Salt is soluble in water.
• Effect of heat: On heating salt a cracking sound is produced due to breaking of ‘ salt crystals.
• Hygroscopic: Salt absorb moisture from the air, This is due to presence of magnesium and calcium chloride.

Reaction with sulphuric acid. Salt reacts with concentrated sulphuric acid to produce HCl gas.

Reaction with silver nitrate. Salt reacts with silver nitrate to form white precipitates of silver chloride.
AgNO₃ + NaCl → AgCl + NaNO₃

Question 17.
Give uses of common salt.
Answer:

• Salt is important constituent of our food.
• This is used as preservative in many eatables.
• It is used in soap, pottery industry.
• It is used in making freezing mixture.
• It is used in the preparation of bleaching powder, caustic soda, hydrochloric acid, washing soda, Baking powder etc.

Question 18.
What is chlor-alkali process? Give pictorial representation of the products of this reaction. Give their uses.
Answer:

Important products of chior-alkali process.

When current is passed through aqueous solution of salt gets dissociated and sodium hydroxide is produced. This is known as chlor-alkali process because the products in this reaction are chlorine (chlore) and sodium hydroxide (base)
2NaCl(aq)+ 2H₂O(l) → 2NaOH(aq) + Cl₂(g) + H₂(g)

All these products are very important and useful in industry medicine, home and cosmetics etc. Chlorine and hydrogen are the by products of this process.

Question 19.
How is bleaching powder prepared? Give its common characteristics and uses.
Answer:
Bleaching powder is obtained by the reaction of chlorine with slaked lime.

To manufacture bleaching powder at large scale, we have a special tower there is a hopper at the top of tower, slaked lime is added through this hopper. At the bottom hot air and chlorine gas are blown. Chlorine moves upwards and is absorbed completely by slaked lime and bleaching powder is produced.

Characteristics :

• Bleaching powder is light yellow coloured powder, It has a sharp smell of chlorine.
• It is soluble in water, but not completely.
• It reacts with CO₂ of air and loose its chlorine.
  CaOCl₂ + CO₂ → CaCO₃ + Cl₂
• It reacts with acids
  CaOCl₂ + 2HCl → CaCl₂ + H₂O + Cl₂
  CaOCl₂ +H₂SO₄ → CaSO₄ + H₂O + Cl₂

Uses

• It is used in paper and textile industry.
• Used to disinfect drinking water to make it free from germs.
• It is used to make unshrinkable work.
• It is used for preparing chloroform.
• It acts as oxidising agent.

Question 20.
Write chemical formula for washing soda. When its crystals are open in air, then what happens?
Answer:
Chemical formula for washing soda is Na₂CO₃. 10H₂O. When its crystals are left open in air then due to efforescence nine molecules of water are lost in the air.
Na₂CO₃.10H₂O → Na₂CO₃ .H₂O + 9H₂O

Question 21.
What happens when solution of sodium hydrogen carbonate is heated? Give chemical reaction for the equation.
Answer:
When sodium hydrogen carbonate solution is heated then carbon dioxide gas is produced and sodium carbonate is produced.

Question 22.
What is common name of the compound CaOCl₂? Name the substance which reacts with chlorine to produce bleaching powder?
Answer:
Common name of compounds CaOCl₂ is bleaching powder. The substance which reacts with chlorine to produce bleaching powder is slaked lime [Ca(OH)₂],

Question 23.
If during the preparation of plaster of Paris the process of heating is not controlled then which substance is formed?
Answer:
Temperature should be maintained at 373 K during the preparation of plaster of Paris. If temperature is not controlled then unhydrated calcium sulphate (CaSO₄) is produced which do not have the properties of plaster of Paris. This is known as dead burnt Plaster.

Question 24.
Explain preparation, properties and uses of baking soda (NaHCO₃).
Answer:
Chemical formula for baking soda is NaHCO₃ and its chemical name is sodium bicarbonate. It is formed when CO₂ is passed through aqueous solution of Na2CO₃.
Na₂CO₃ + CO₂ + H₂O → 2NaHCO₃

It can also be prepared from sodium chloride.

Properties: When it is heated it swells and becomes light. On heating it produces CO₂. It is soluble in water.

Uses :

• It is used in the preparation of baking powder.
• It acts as antacid in case of acidity in the stomach.
• It is also used in soda-acid fire extinguishers.

Question 25.
Explain the following processes.
(i) Deliquescence
Answer:
Deliquescence: When some compounds absorb moisture from air and change to solution then this process is called deliquescence.
e.g. common salt is deliquescence.

(ii) Bleach.
Answer:
Bleach: When some gas or compound decolourises something, this is known as bleach, e.g. bleaching powder or chlorine is used for this purpose.

Question 26.
What happens when carbon dioxide is passed through fresh lime water?
Answer:
When carbon dioxide is passsed through fresh lime water in small quantity then insoluble calcium carbonate is formed and colour of lime water turns to milky.

If excess of CO₂ is passed through this solution, calcium carbonate change to soluble bicarbonate and milkiness disappears.

If this solution is heated again, milky colour again appears because calcium bicarbonate again change to calcium carbonate.

Question 27.
What is pH scale? How does it respresent acidic and basic nature of a solution? Represent whole range of pH and [H₃O]⁺.
Answer:
A scale which is used to know the concentration of hydrogen ion in a solution is called pH scale. Here ‘p’ stands for ‘potenz’ a German word which means power. We can measure from zero to 14 on this scale. Zero represents strongest acid, and 14 represents strongest base. pH is such a number which represents acidic or basic nature of a solution. More is the concentration of hydrogen ion in a solution less is its pH value. If a solution is neutral its pH value is 7. If pH is lower than 7 then solution is acidic and if pH is more than 7 then solution is basic. Normally pH can be found by using universal pH indicator paper.

Question 28.
Are salt crystals really dry? Explain.
Answer:
Copper sulphate crystals which seems to be dry contains water of crystallization. These seem to be dry hut are not. When we heat the crystals then this water is removed and colour of salt become white. When salt is made wet its colour again change to blue.

Fixed number of molecules of water present in unit formula of salt is called water of crystallization. In unit formula of copper sulphate, there are five molecules of water. Formula for hydrated copper sulphate is CuSO4. 5H2O. In Na₂CO₃.10H₂O there are 10 molecules of water.

Gypsum is another salt which contains water of crystalization. There are two molecules of water in it.
Its formula is CaSO₄.2H₂O.

Question 29.
How is washing soda prepared? Give its uses.
Answer:
Washing soda (Na₂CO₃.10H₂O) is obtained from sodium chloride. By heating soda, we get sodium carbonate. By recrystallization of sodium carbonate, washing soda is obtained. This is a basic salt.

Sodium carbonate and sodium bicarbonate are useful in several industrial processes.

Uses of washing soda :

• Sodium carbonate is used in glass, soap and paper industry.
• It is used in the manufacturing of sodium compound such as Borax.
• It is used in cleaning agent for domestic purpose.
• It is used to remove permanent hardness of water.

Question 30.
What is efflorescence? Name one compound which shows efflorescence? Explain your answer with an equation.
Answer:
The phenomenon of losing some part of water of cyrstallization into air from a crystal is called efflorescence. This phenomenon takes place on heating or some times spontaneously. Washing soda contain water of crystallization hence its formula is Na₂CO₃. 10H₂O. When it is placed in open then it loose its 9 molecules of water and single hydrate is left.
Na₂CO₃.10H₂O → Na₂CO₃.H₂O + 9H₂O

on heating it looses all of its water.
Na₂CO₃.10H₂O → Na₂CO₃ + 10H₂O

Question 31.
A baker found that a cake prepared by him is small in size and hard. Which constituent, he forgot to add, due to which cake can become soft and big. Give reason.
Answer:
Baker forgot to add baking powder. When baking powder (a mixture of sodium bicarbonate and Tartaric acid) is added to cake and on heating tartaric acid reacts with sodium bicarbonate to produce carbon dioxide. This carbon dioxide makes the cake to swell and cake becomes light. Baker, definitely forgot to add baking powder that is why cake is small and hard.

Question 32.
When bleaching powder is left open in air, then what happens?
Answer:
When bleaching powder is left open in air, then its properties change. C02 present in air reacts with it due to which calcium carbonate and chlorine gas are produced. Properties of bleaching are lost.
CaOCl₂ + CO₂ → CaCO₃ + Cl₂

Question 33.
What are the important uses of bleaching powder?
Answer:

• It is used to bleach cotton cloths, linen and wood pulp.
• It is used to disinfect drinking water and to make it free of germs.
• It is used to make chloroform.
• Unshrinkable wool is prepared using bleaching powder.
• It acts as oxidizing agent in Laboratories and in industry.

Question 34.
Name the compounds used in hospitals for supporting fractured bones in the right position. How is it prepared?
Answer:
The compound used in hospitals for supporting fractured bones in the right position is plaster of paris. It is calcium sulphate hemihydrate (CaSO₄. \(\frac{1}{2}\)H₂O). It is prepared at a temperature of 373 K by heating gypsum.

Question 35.
Write important uses of Plaster of Paris.
Answer:

• It is used in making toys, moulds, ceramic, containers etc.
• It is used for making material for decoration and statues.
• In hospitals it is used by doctors to set fractured bones and by dental doctors for creating mould to make dentures.
• Used in buildings, to give plane look to walls and ceiling.
• Material used by fire fighters.
• It is used to stop leakage of gases in Laboratories.

Question 36.
Many people complaint about gas problem in stomach. What is main reason for this? Why do they use ‘milk of magnesia’ to get relief from this?
Or
What are antacids?
Answer:
A juice is secreted in the stomach which contains enzyme pepsine and hydrochloric acid. Enzyme pepsine is active in acidic medium. When hdyrochloric acid is produced in excess quantity, then we get burning and pain in the stomach, which is known as acidity.

Those substances which are used to neutralize this acid are called antacids. Usually people take a mild base like milk of magnesia for this purpose. It neutralizes the excess acid and provide relief.

Question 37.
Idols and utensils made up of copper and brass become shiny when rubbed with lemon? Why?
Answer:
Idols and utensils made up of copper and brass become dull due to coating of copper oxide. Citric acid present in lemon react with it to form salt, which can be easily washed with water. Brass and copper surface becomes shiny.

Question 38.
For the safety of teeth what type of toothpaste should be used. Why?
Or
How does change in pH-value helps in tooth decay?
Answer:
Bacteria present in mouth produce acid by degradation of sugar and food particles. This reduces the pH value of mouth which causes tooth decay. After foods we should used basic tooth pastes to prevent tooth decay. Mild bases present in it neutralizes the excess acid. This reducing the chances of tooth decay.

Question 39.
What is the remedy for sting of Nettle plant? Write.
Answer:
Nettle is a herbaceous plant found in jungles. Its leaves have stinging hair. These hair cause painful sting if touched accidentally. This pain is due to the secretion of methanoic acid by stinging hair in the body. To get rid of this pain leaves of dock plant are rubbed on the area of sting. Leaves of dock plant have base in them. This plant often grows beside the nettle plant. It neutralizes the acidic effect and gives relief from pain.

Question 40.
What is acidic rain? How is the pH of soil can be measured?
Answer:
Some of the gases like SO₂, SO₃, NO₂ etc. present in the atmosphere gets dissolved in rain water and fall on earth in the from of acid is called acid rain. This corrodes some of the metals and marble.

pH value of soil can be measured by using paper soaked in universal indicator. This way we can know the nature of soil as acidic or basic. When pH value of rain water is less < than 5-6 then it is called acid rain. To know the pH value of soil, it is dissolved in water in a test tube and its filter is tested with universal indicator pH paper.

Question 41.
Is human life possible on venus planet?
Answer:
No, human life is not possible on venus plant the atmosphere of venus is covered with thick white and yellow clouds of sulphuric acid. If there is a rain is presence of water, it will be acidic and the existence of human life will be impossible.

Question 42.
Magnesium is treated with dil. H₂SO₄. The gas evolved is collected as shown below. Name the method used for collection of gas and the gas produced.

Answer:
Downward displacement of water. The gas produced is hydrogen.

Question 43.
Compounds such as alcohols and glucose also contain hydrogen but are not categorised as acids. Describe an activity to prove it.

Answer:
Fix two nails on a cork and place it in a 100 ml beaker. Connect thses nails to a 6 volt battery through a bulb and switch as shown in the figure.

Pour some aqueous solution of alcohol or aqueous solution of glucose in the beaker so that nails dip in it. Switch on the current. The bulb does not glow indicating that alcohol and glucose don’t dissociate in aqueous solution and hence do not produce H⁺_(aq) ions although they contain hydrogen.

Aqueous solution of alcohol or glucose does not conduct electricity

1 — Cathode
2 — Anode

Question 44.
Observe the figure and answer the following:

(i) What are 1 and 2?
Answer:
1-Soap bubble filled with hydrogen 2-Burning of hydrogen gas with a pop sound

(ii) Write down the reactions taking place in test tube.
Answer:

Question 45.
In the pH paper shown in figure given below, pH of lemon juice is 2.2 and that milk of magnesia is 10. What is its significance?

Answer:

• Lemon justice is acidic because pH is less than 7.
• Milk of magnesia is basic because pH is more than 7.

Question 46.
Which gas is being produced during reaction in the test tube? How does this gas react with Calcium Hydroxide/Lime water?

Answer:
Carbon dioxide (CO₂).

Very Short Answer Type Questions

Question 1.
What makes food sour?
Answer:
Presence of acids.

Question 2.
What is the reason of bitterness?
Answer:
Presence of bases.

Question 3.
What is the reason of acidity in stomach?
Answer:
excess of HCl acid.

Question 4.
What is the effect of acid on litmus?
Answer:
Blue litmus changes to red.

Question 5.
What are olfactory indicators?
Answer:
Some substances which change their smell in acidic or basic medium are called . olfactory indicators.

Question 6.
Give three examples of olfactory indicators.
Answer:
Chopped onions, clove coil, vanilla essence.

Question 7.
Which gas is produced when Zinc reacts with sodium hydroxide?
Answer:
Hydrogen gas.

Question 8.
Which gas is produced when metal carbonates and metal hydrogen carbonates react with acid?
Answer:
Carbon dioxide.

Question 9.
What happens when CO₂ is passed through lime water?
Answer:
Lime water turns milky.

Question 10.
Why milkiness of lime water disappear when excess of CO₂ is passed through it?
Answer:
Due to formation of Ca(HCO₃)₂ which is soluble in water.

Question 11.
Write the name and colour of the compound formed when copper oxide reacts with dilute hydrochloric acid.
Answer:
Blue-green copper chloride.

Question 12.
Which name is used for metal oxide?
Answer:
Alkaline oxide.

Question 13.
What is the nature of non-metal oxide?
Answer:
Acidic nature.

Question 14.
Why does current flow in acids?
Answer:
Due to ions.

Question 15.
Which ion is produced in acidic solution?
Answer:
Hydrogen ion (H+).

Question 16.
What is used to dry, moist gas?
Answer:
Calcium chloride.

Question 17.
How do we represent hydrogen ion?
Answer:
H⁺_(aq) or hydronium ion (HgO⁺).

Question 18.
Which ions is produced by bases in water?
Answer:
Hydroxide (OH^–) ion.

Question 19.
What is base?
Answer:
Alkalies which are soluble in base.

Question 20.
What should we do to dilute an acid?
Answer:
We should add acid to water slowly and not vice versa.

Question 21.
What is dilution?
Answer:
When we add acid or base in water, concentration of ions (HgO⁺/OH^–) per unit volume decreases, this is known as dilution.

Question 22.
What is name of mixture of various indicators?
Answer:
Universal indicator.

Question 23.
What is that which show different colour at different concen-tration of hydrogen ion in a solution?
Answer:
Universal indicator.

Question 24.
What is pH scale?
Answer:
To know the strength of H⁺ ion in a solution a scale is used known as pH scale.

Question 25.
What is p in pH?
Answer:
‘p’ means ‘potenz’.

Question 26.
What is the range of pH scale?
Answer:
0 to 14.

Question 27.
What is pH value of neutral solution?
Answer:
pH value is 7.

Question 28.
If pH value of solution is less than 7, then what does it indicate?
Answer:
Acidic solution.

Question 29.
If pH value of a solution is more than 7, then what does it indicate?
Answer:
Solution is basic.

Question 30.
What is the value on pH scale for lemon juice?
Answer:
Nearly 2.2.

Question 31.
What is the value on pH scale for pure water?
Answer:
7

Question 32.
What is the value on pH scale for milk of magnesia?
Answer:
10.

Question 33.
What is the value on pH scale for sodium hydroxide?
Answer:
Nearly 14.

Question 34.
What is pH range in which our body works?
Answer:
Our body works in the pH range of 7.0 to 7.8.

Question 35.
What is pH value of acid rain?
Answer:
It is less than 5.6.

Question 36.
In which type of river survival of aquatic animals is difficult?
Answer:
When acid rain water flows to the river.

Question 37.
What surrounds the venus planet?
Answer:
Thick white and yellow clouds of sulphuric acid.

Question 38.
Which acid is produced in our stomach?
Answer:
Hydrochloric acid.

Question 39.
What is produced in the stomach when there is indigestion.
Answer:
Excess of HCl.

Question 40.
What is used for treating excess of acid in the stomach?
Answer:
Antacids (mild bases).

Question 41.
When does tooth decay begin?
Answer:
When pH value in less than 5.5.

Question 42.
Teeth are made up of which substance?
Answer:
Calcium phosphate.

Question 43.
Why do we feel pain due to bee sting?
Answer:
Due to acid.

Question 44.
Which substance is applied on the stinging area which gives relief from pain?
Answer:
Weak base like baking soda.

Question 45.
What do the stinging hair of nettle plant secret?
Answer:
Methanoic acid.

Question 46.
What is the remedy for sting of herbaceous plant Nettle?
Answer:
Rub leaves of dock plant.

Question 47.
Which acid is there in vinegar?
Answer:
Acetic acid.

Question 48.
Which acid is there in lemon, orange?
Answer:
Citric acid.

Question 49.
Which acid is in curd and milk?
Answer:
Lactic acid.

Question 50.
What is main source of salt?
Answer:
Sea water.

Question 51.
What is exothermic reaction?
Answer:
Those chemical reactions in which heat is produced.

Question 52.
What is endothermic reaction?
Answer:
Those chemical reactions in which heat in absorbed are called endothermic reactions.

Question 53.
Solid sodium chloride does not conduct electric current, why?
Answer:
In sodium chloride, Na+ and Cl- ions are held together by strong electrostatic forces of attraction and ions can’t move freely. Hence solid sodium chloride does not conduct electric current.

Question 54.
In which state chemical reactions take place easily.
Answer:
Gaseous or liquid state.

Question 55.
What is solute?
Answer:
It is a compound, which in aqueous solution, dissociate into positive and negative ions.

Question 56.
What is a strong electrolyte?
Answer:
A compound which dissociate in water and its dissociation percentage is 30%, is called strong electrolyte.

Question 57.
What is weak electrolyte?
Answer:
A compound which dissociate in water and its dissociation percentage is less than 30% is called weak electrolyte.

Question 58.
Which acids are obtained from animals?
Answer:
Organic acids.

Question 59.
Who gave pH scale and when?
Answer:
pH scale was given by Danish Chemist Soren Sorensen in 1909.

Question 60.
Concentration of which ion is important in every Biological and many industrial processes?
Answer:
Concentration of hydrogen ion.

Question 61.
What is the reason for burn feeling in stomach and chest? How to get rid of this situation?
Answer:
When excess of hydrochloric acid is produced in stomach, then we feel burn feeling in stomach and chest. We can be relieved by taking baking soda.
NaHCO₃ + HCl → NaCl + H₂O + CO₂

Question 62.
What is baking powder?
Answer:
Baking powder is a mixture of baking soda and tartaric acid.

Question 63.
If we do not use tartaric acid in baking powder for making a cake. How will the cake taste?
Answer:
It will be bitter due to sodium carbonate.

Question 64.
Which chemicals are used in fire extinguishers?
Answer:
Sodium hydrogen carbonate and sulphuric acid.

Question 65.
Which gas is produced in soda acid fire extinguisher?
Answer:
Carbon dioxide gas.

Question 66.
Which compound is used to make water free of germs?
Answer:
Bleaching powder (CaOCl₂).

Question 67.
Name chemical name of quick lime.
Answer:
Calcium oxide (CaO).

Question 68.
Name the deliquescent present in salt.
Answer:
Magnesium chloride (MgCl₂).

Question 69.
What type of smell is given by bleaching powder?
Answer:
Smell of ehlorme gas.

Question 70.
Sometimes eyes become red after swimming in a swimming pool why?
Answer:
Due to excess of bleaching powder in water.

Question 71.
When did Egyptions used plaster of paris?
Answer:
They used it 5000 years ago.

Question 72.
How did the Egyptions prepare plaster of Paris?
Answer:
They heated Gypsum in open air.

Question 73.
What was the use of Plaster of Paris for Egyptions?
Answer:
They used to fix rocks with it as cement for their monuments.

Question 74.
What is the relation of ‘Paris’ in plaster of Paris?
Answer:
In the beginning Gypsum was obtained from Montmarti in Paris, thus paris is related with it.

Question 75.
What is heated to which temperature from preparing plaster of Paris?
Answer:
Plater of Paris is obtained from gypsum (CaSO₄.2H₂O) by heating it to 373 K.

Multiple Choice Questions:

Question 1.
pH of an acidic solution is:
(A) >7
(B) <7
(C) 7
(D) 14.
Answer:
(B) <7

Question 2.
Neutral solution has pH:
(A) 7
(B) >7
(C) < 7
(D) 14.
Answer:
(A) 7

Question 3.
Common name of NaCO₃. 10H₂O is :
(A) Bleaching powder
(B) Baking powder
(C) Plaster of Paris
(D) Washing soda.
Answer:
(D) Washing soda.

Question 4.
Acid and base react to form salt and water. This reaction is called:
(A) Washing soda.
(B) Chioro-alkali
(C) Reduction
(D) None of these.
Answer:
(D) None of these.

Question 5.
What is used for plastering fractured bones?
(A) Cement
(B) Gypsum
(C) Plaster of Paris
(D) Soda.
Answer:
(C) Plaster of Paris

Question 6.
Toothpaste used for cleaning teeth is :
(A) Acidic
(B) Neutral
(C) Basic
(D) None.
Answer:
(A) Acidic

Question 7.
A solution turns red litmus blue, its pH is :
(A) 1
(B) 4
(C) 5
(D) 10
Answer:
(D) 10.

Fill in the blanks:

Question 1.
The common name of CaOCl₂ is ______
Answer:
Bleaching powder.

Question 2.
The sodium compound used for softening hard water is ______
Answer:
Washing soda.

Question 3.
The common name of Na₂CO₃.10H₂O is ______
Answer:
Washing soda.