CHAPTER – 1 : CHEMICAL REACTIONS AND EQUATIONS

SECTION - A
I. Choose the correct answer:

1. Quick lime combines vigorously with water to form (A) which reacts slowly with the carbon dioxide in
air to form (B). Identify the compounds (A) and (B).

A B
a. Calcium carbonate Calcium hydroxide
b. Calcium hydroxide Calcium carbonate
c. Calcium Calcium bicarbonate
d. Calcium bicarbonate Calcium

2. Which among the following is/are double displacement reaction(s)?

(i) Pb + CuCl2 → PbCl2+ Cu (ii) Na2SO4 + BaCl2 → BaSO4 + 2NaCl
(iii) C + O2 → CO2 (iv) CH4 + 2O2 → CO2 + 2H2O
(a) Only (ii) (b) (i) and (iv) (c) (iii) and (iv) (d) (i) and (ii)

3.The following reaction is used for the preparation of oxygen gas in the laboratory:
2KClO3(s) Catalyst →heat 2KCl(s) + 3O2 (g)

Which of the following statement(s) is(are) correct about the reaction?

(a) It is a combination reaction.
(b) It is a decomposition reaction and endothermic in nature.
(c) It is a photochemical decomposition reaction and exothermic in nature.
(d) It is a decomposition reaction and accompanied by release of heat.

4. A student added 10 g of calcium carbonate in a rigid container, secured it tightly and started to heat it.
After some time, an increase in pressure was observed, the pressure reading was then noted at intervals of
5min and plotted against time, in a graph as shown below. During which time interval did maximum
decomposition took place?

(a) 10-15 min (b) 15-20 min (c) 0-5 min (d) 5-10 min

5. The reaction that differs from the rest of the reaction given is-
(a) formation of calcium oxide from limestone
(b) formation of aluminium from aluminium oxide
(c) formation of sodium carbonate from sodium hydrogen carbonate
(d) formation of mercury from mercuric oxide

6. Magnesium ribbon is rubbed with sand paper before making it to burn. The reason of rubbing the ribbon
is to:

(a) remove moisture condensed over the surface of ribbon.

(b) generate heat due to exothermic reaction.
(c) remove magnesium oxide formed over the surface of magnesium.
(d) mix silicon from sand paper (silicon dioxide) with magnesium for lowering ignition temperature of the
ribbon.

7. Exposure of silver chloride to sunlight for a long duration turns grey due to.

Which among the following statement(s) is(are) true?

1. the formation of silver by decomposition of silver chloride. 2. sublimation of silver chloride.
3. decomposition of chlorine gas from silver chloride. 4. oxidation of silver chloride.
(a) Only 1 (b) 1 and 3 (c) 2 and 3 (d) Only 4

8. The necessary conditions for combustion process to occur are

1. availability of air/oxygen. 2. availability or air/oxygen and fuel.

3. temperature of fuel below ignition temperature. 4. temperature of fuel above ignition temperature.
Select the correct alternative.
(a) 1 and 2 (b) 2 and 4 (c) 3 and 1 (d) 4 and 1

9. Which of the following is not a chemical reaction?

(a) Souring of milk (b) Dissolution of sugar in water
(c) Rusting of iron (d) Digestion of food in the body
10. Fe2O3 + 2Al → Al2O3 + 2Fe The above reaction is an example of a-
(a) combination reaction (b) double displacement reaction
(c) decomposition reaction (d) displacement reaction

11. Calcium oxide reacts vigorously with water. Which of the following is the incorrect observation of the
reaction shown in the above set up?

(a) It is an endothermic reaction (b) Slaked lime is produced

(c) It is an exothermic reaction (d) It is a combination reaction

12. N2 + 3H2 → 2NH3

With the reference of above reaction which one of the option in the table is correct?
Reactants Products
(a) N2 , H2 NH3
(b) NH3 N2 , H2
(c) N2 H2 , NH3
(d) N2 NH3 H2

13. The following reaction is an example of a - 4NH3(g) + 5O2(g)→ 4NO(g) + 6H2O(g)

1. displacement reaction 2. combination reaction 3. redox reaction 4. neutralisation reaction
(a) 1 and 4 (b) 2 and 3 (c) 1 and 3 (d) 3 and 4

14. The reaction between carbon and oxygen can be represented as

C(s) + O2(g) →∆ CO2 (g) + Heat
In which of the following type(s), the above reaction can be classified?
1. Combustion reaction 2. Displacement reaction 3. Endothermic reaction 4. Combination reaction
(a) 1 and 3 (b) 1, 3 and 4 (c) 1 and 4 (d) 1 Only

15. Which of the following reaction is characterised by the yellow colour of product?
(a) 2Pb3O4 ∆→ 6PbO(s) + O2(g) (b) Zn(s) + H2SO4 → ZnSO4 + H2
(c) Na2CO3 + H2SO4 → Na2SO4 + H2O + CO2 (d) 2KClO3 ∆→ 2KCl + 3O2(g)

16. Silver articles become black on prolonged exposure to air as shown in the figure. This is due to the
formation of

(a) Ag3N (b) Ag2O (c) Ag2S (d) Ag2S and Ag3N

17. The statement of law of conservation of mass is:

(a) mass can neither be created nor destroy (b) mass can be created nor destroy.
(c) mass of the body cannot be remain same (d) none of these.

18. Which of the following statements about the given reaction are correct?
3Fe(s)+4H2O(g)→Fe3O4(s)+4H2(g)
(i) Iron metal is getting oxidised (ii) Water is getting reduced
(iii) Water is acting as reducing agent (iv) Water is acting as oxidising agent
(a) (iii) and (iv) (b) (i),(ii) and (iv) (c) (ii) and (iv) (d) (i),(ii) and (iii)

19. Sodium hydrogen carbonate when added to acetic acid evolves a gas. Which of the following statements
are true about the gas evolved?
(i) It turns lime water milky. (ii) It extinguishes a burning splinter.
(iii) It dissolves in a solution of sodium hydroxide. (iv) It has a pungent odour.
(a) (i) and (ii) (b) (i), (ii) and (iii) (c) (ii), (iii) and (iv) (d) (i) and (iv)

20. If copper is kept open in air, it slowly loses its shining brown surface and gains a green coating. It is due
to the formation of:
(a) CuSO4 (b) CuCO3 (c) Cu(NO3)2 (d) CuO

21. CuO(s) + H2(g) → Cu(s) + H2O(l)

Which of the following pair is correct regarding to oxidation and reduction?
Or
Identify the substances that is oxidized and the substances that is reduced in the following reactions:
(a) H2 , CuO (b) H2 , H2O (c) H2 , Cu (d) Cu, H2

22. The given diagram represents a ____reaction.

(a) Thermal decomposition (b) Displacement (c) Double displacement (d) Combination

23. Complete the following chemical reaction with correct option:

Pb(NO3)2 + 2KI → ___________ + 2KNO3
(a) PbI2 (b) PbNO3 (c) Pb(NO3)2 (d) PbIO3

24. Which of the following substances will not give carbon dioxide on treatment with dilute acid?
(a) Marble (b) Limestone (c) Baking soda (d) Lime

25. Which of the following are exothermic processes?

1. Reaction of water with quick lime. 2. Dilution of an acid.
3. Evaporation of water. 4. Sublimation of camphor (crystals).
(a) 1 and 2 (b) 2 and 3 (c) 1 and 4 (d) 3 and 4

26. When hydrogen sulphide gas is passed through a blue solution of copper sulphate, a black precipitate of
copper sulphide is obtained and the sulphuric acid so formed remains in the solution. The reaction is an
example of-
(a) A combination reaction (c) A displacement reaction
(c) a decomposition reaction (d) A double decomposition reaction

27. Galvanisation is a method of protecting iron from rusting by coating with a thin layer of:
(a) aluminium (b) gallium (c) silver (d) zinc

28. Following observations are observed when calcium oxide reacts vigorously with water. Identify the
incorrect observations.

(i) It is an endothermic reaction. (ii) Slaked lime is produced.

(iii) Quick lime is produced. (iv) It is an exothermic reaction.
(v) It is a combination reaction.
(a) (iii) and (iv) (b) (i) and (ii) (c) (ii), (iv) and (v) (d) (i) and (iii)

29. Rahul is a skilled painter. He mixed a white coloured powder, compound X with water. The compound X
reacted vigorously with water to produce a compound Y and a large amount of heat. Then, Rahul used the
compound Y for white washing the walls.

Name the compound Y that Rahul got after mixing X with water.
(a) Calcium oxide (b) Calcium (c) Calcium hydroxide (d) Calcium carbonate

30. Which of the following statements about the given reaction are correct?
3Fe(s) + 4H2O(g) → Fe3O4(s) + 4H2(g)
(i) Iron metal is getting oxidised (ii) Water is getting reduced
(iii) Water is acting as reducing agent (iv) Water is acting as oxidising agent
(a) (iii) and (iv) (b) (i),(ii) and (iv) (c) (ii) and (iv) (d) (i),(ii) and (iii)

31. Oxygen gas reacts with hydrogen to produce water. The reaction is represented by the equation:
O2(g) + H2(g) → H2O(I) The above reaction is an example of
1. Oxidation of hydrogen 2. Reduction of oxygen
3. Reduction of hydrogen 4. Redox reaction
(a) 1, 2 and 3 (b) 2, 3 and 4 (c) 1, 3 and 4 (d) 1, 2 and 4

32. What happens when copper rod is dipped in iron sulphate solution?

(a) Copper displaces iron (b) Blue colour of copper sulphate solution is obtained
(c) No reaction takes place (d) Reaction is exothermic
33. A dilute ferrous sulphate solution was gradually added to the beaker containing acidified permanganate
solution. The light purple colour of the solution fades and finally disappears. Which of the following is the
correct explanation for the observation?
(a) KMnO4 is an oxidising agent, it oxidises FeSO4 .
(b) FeSO4 acts as an oxidising agent and oxidises KMnO4 .
(c) The colour disappears due to dilution; no reaction is involved.
(d) KMnO4 is an unstable compound and decomposes in presence of FeSO 4 to a colourless compound.

34. In the reaction of iron with copper sulphate solution:

CuSO4 + Fe → Cu + FeSO4
Which option in the given table correctly represents the substance oxidised and the reducing agent?
Option Substance oxidised Reducing agent
a. Fe Fe
b. Fe FeSO4
c. Cu Fe
d. CuSO4 Fe

35. The diagram shows the electrolysis of water. A few drops of H2SO4 are added to pure water because :

(a) pure water is a bad conductor of electricity (b) it does not conduct electricity
(c) Both (a) and (b) (d) it makes the reaction faster

36. Which of the following correctly represents a balanced chemical equation?

(a) 3Fe(s) + 4H2O(g) → Fe3O4 (s) + 4H2O(g) (b) 3Fe(s) + 4H2O(g) → Fe3O4 (s) + 4H2(g)
(c) Fe(s) + 4H2O(g) → Fe3O4 (s) + 4H2O(g) (d) 3Fe(s) + H2O(g) → Fe3O4 (s) + H2(g)

37. Identify gas A in the following experiment.

(a) Hydrogen (b) Nitrogen (c) Carbon dioxide (d) Oxyge

38. Y + 2HCl → ZnCl2 + H2 . In the above reaction, Y is

(a) Aluminium (b) Copper (c) Sodium (d) Zinc

Which of the following pair is correct.

Reaction Reaction Types

a) 2KNO3(s) → 2KNO2(s) + O2(g) Displacement reaction
b) Zn(s) + 2AgNO3(aq) → Zn(NO3)2 + 2Ag(s) Combination reaction
c) Ni(NO3)2(aq) + 2NaOH→ Ni(OH)2 l + 2NaNO3(aq) Double displacement and precipitate reaction
d) N2(g) + 3H2(g) → 2NH3(g) Decomposition reaction
39. Which of the following is correct for a physical change?
i) only physical properties change. ii) large amount of heat is observed or evolved.
(a) only (i) (b) only (ii) (c) both (i) and (ii) (d) neither (i) and (ii)

40. Metal reacts with water and produce a metal oxide and hydrogen gas. Metal oxides that are soluble in
water dissolve in it to further form metal hydroxide. But all metals do not react with water. Which of the
following statement is correct regarding to physical changes?
(a) In physical change, new substance is formed (b) In physical change, no new substance is formed.
(c) In physical change, chemical composition of substance is changed (d) None of these

41. Which one reaction shows the property of double displacement reaction?
(a) CuSO4 + Zn → ZnSO4 + Cu (b) Cu + 2AgNO3 → Cu(NO3)2 + 2Ag
(c) NaOH + HCl → NaCl + H2O (d) None of these

42. Which of the following is/are combination reaction(s)?

(i) 2KClO3Heat→2KCl+3O2 (ii) MgO+H2O→Mg(OH)2
(iii) 4Al+3O2→2Al2O3 (iv) Zn+FeSO4→ZnSO4+Fe
(a) 1 and 3 (b) 3 and 4 (c) 2 and 4 (d) 2 and 3

43. Match the chemical substances given in column (A) with their appropriate application given in column
(B)
Column (A) Column (B)
A. Bleaching powder (i) Preparation of glass
B. Baking soda (ii) Production of H2 and Cl2
C. Washing soda (iii) Decolorization
D. Sodium chloride (iv) Antacid

(a) A- (ii), B- (i), C- (iv), D- (iii) (b) A- (iii), B- (ii), C- (iv), D- (i)
(c) A- (iii), B- (iv), C- (i), D- (ii) (d) A- (ii), B- (iv), C- (i), D- (iii)

44. In the following practical set which of the following gas is emitted?

(a) Hydrogen (b) Carbon monoxide (c) Carbon dioxide (d) Nitrogen

45 When lead nitrate crystals are heated as shown in the figure:

(a) a brown gas is evolved and a white residue is left behind
(b) a colourless gas is evolved and a yellow residue is left behind
(c) a brown gas is evolved and a yellow residue is left behind.
(d) a greenish yellow gas is evolved and a brown residue is left behind

46. Study the experimental set up shown in given figure and choose the correct option from the following:

P Q Change observed in Ca(OH)2 solution

a K2CO3 Cl2 No change
b KHCO3 CO2 No change
c KHCO3 H2 Turns milky
d K2CO3 CO2 Turns milky

47. Which of the following measures can be adopted to prevent or slow down rancidity?
(i) Food materials should be packed in air tight container.
(ii) Food should be refrigerated.
(iii) Food materials and cooked food should be kept away from direct sunlight.
(a) I and III (b) II and III (c) II and I (d) I, II and III

48. Which of the following pair is incorrect in the given table?

Reaction Reaction Name
(a) CH4 + 2O2 → CO2 + 2H2O Combustion reaction and oxidation reaction
(b) Pb(NO3)2 + 2KI → PbI2 + KNO3 Double displacement and precipitation reaction
(c) CaO + H2O → Ca(OH)2 Combination reaction
(d) CuSO4 + Zn → ZnSO4 + Cu Combination reaction

49. When hydrogen sulphide gas is passed through a blue solution of copper sulphate, a black precipitate of
copper sulphide is obtained and the sulphuric acid so formed remains in the solution. The reaction is an
example of:
(a) combination reaction (b) displacement reaction
(c) decomposition reaction (d) double displacement reaction

50. The schematic diagram is given below :

51. Which of the following is an incorrect statement?
(a) A and E are chemically same (b) A and D are chemically same.
(c) D and E are chemically same (d) C and E are chemically same.

52. Which of the following is an example of displacement reaction?

(a) NaOH + HNO3 → NaNO3 + H2O (b) Cu + 2AgNO3 → Cu(NO3)2 + 2Ag
(c) 2Hg + O2 → 2HgO (d) FeCl3 + 3NaOH → 3NaCl + Fe(OH)3

53. Rusting of iron can be prevented by:

1. Painting 2. Galvanisation 3. Electrolytic refining 4. Alloying
Which of the above are correct?
(a) 1, 2 and 3 (b) 1, 2 and 4 (c) 2, 3 and 4 (d) 1, 2, 3 and 4

54. Which of the following is a feasible reaction?

(a) Ba(s) + K2SO4(aq)→BaSO4(aq) + 2K(s) (b) Zn(s) + 2AgNO3(aq)→Zn(NO3)2(aq) + 2Ag(s)
(c) Mg(s) + Na2SO4(aq)→MgSO4(aq) + 2Na(s) (d) Cu(s) + MgSO4(aq)→CuSO4(aq) + Mg(s)

55. Some of the substances used in making of a modern safety match box are listed below :
1. Antimony trisulfide 2. Glass powder 3. Potassium chlorate 4. Red phosphorus
The head of modern safety match stick contains :
(a) 1 and 4 (b) 2 and 3 (c) 3 and 4 (d) 3 and 1

56. The colour of the crystals before heating and after heating are respectively:

(a) Pale green, Reddish brown (b) Reddish brown, Pale green
(c) Reddish brown, Reddish brown (d) Pale green, Pale green

57. Which of the following are correctly matched?

1. Dissolution - Solute gets dissolved in a solvent.
2. Exothermic - Heat in absorbed.
3. Reversible change - Reactants can be obtained.
Which of the above are correct?
(a) 1 and 2 (b) 2 and 3 (c) 1 and 3 (d) 1, 2 and 3
58. A metal is treated with dilute sulphuric acid. The gas evolved is collected by the method shown in the
figure.

The name of the gas is

(a) Hydrogen (b) Oxygen (c) Nitrogen (d) Helium

59. Which one of the following is the example of oxidation?

(a)2Mg(s) +O2(g) → 2MgO(s) (b)CuO(s) + H2(g) ∆→ Cu(s) +H2O(g)
(c) Fe2O3(s) + 2Al(s) ∆→ Al2O3(s) +2Fe(s) (d) None of these

60. The reaction 2Na + Cl2 → 2NaCl is an example of _______ reaction.

(a) combination (b) decomposition (c) displacement (d) double displacement

61. Which of the following is the observations of the chemical reaction?

1. Change in state 2. Evolution of a gas 3. Change in colour 4. Change in temperature
(a) 1, 2 and 3 (b) 1, 2 and 4 (c) 1, 3 and 4 (d) 1, 2, 3 and 4

62. In the double displacement reaction between aqueous potassium iodide and aqueous lead nitrate, a
yellow precipitate of lead iodide is formed. While performing the activity if lead nitrate is not available,
which of the following can be used in place of lead nitrate?
(a) Lead sulphate (insoluble) (b) Lead acetate (c) Ammonium nitrate (d) Potassium sulphate

63. The physical change is:

(a) melting of butter (b) burning of paper (c) digestion of food (d) bursting of crackers

64. Translate the following statement into the chemical equation and choose the correct option “Hydrogen
gas combines with nitrogen to form ammonia.”
(a) 3H2(g) + N2(g) → 2NH3(g) (b) H2(g) + N2(g) → NH3(g)
(c) 2H2 (g) + N2 (g) → 3NH3(g) (d) None of these

65. What happens when dilute hydrochloric acid is added to iron fillings? Tick the correct answer :
(a) Hydrogen gas and iron chloride are produced (b) Chlorine gas and iron hydroxide are produced.
(c) No reaction takes place (d) Iron salt and water are produced

66. Which of the following is not a chemical change?

(a) Burning of a candle (b) Cooking a food (c) Sublimation (d) Germination of seeds

67. When the gases sulphur dioxide and hydrogen sulphide mix in the presence of water, the reaction is
SO2 + 2H2S → 2H2O + 3S
Here hydrogen sulphide is acting as:
(a) an oxidising agent (b) a reducing agent (c) a dehydrating agent (d) a catalyst

68. Barium chloride on reacting with ammonium sulphate forms barium sulphate and ammonium chloride.
Which of the following correctly represents the type of the reaction involved?
1. Displacement reaction 2. Precipitation reaction
3. Combination reaction 4. Double displacement reaction
(a) Only 1 (b) Only 2 (c) Only 4 (d) 2 and 4

69. Which of the following are correctly matched in the given table?
1. Combination reaction - Formation of single product.
2. Decomposition reaction - Break down of single, entity.
3. Thermal decomposition - Heat is used.
4. Displacement reaction - Based on reactivity series.
(a) 1, 2 and 3 (b) 1, 2 and 4 (c) 1, 3 and 4 (d) 1, 2, 3 and 4

70. Solid calcium oxide reacts vigorously with water to form calcium hydroxide accompanied by liberation
of heat. This process is called slaking of lime. Calcium hydroxide dissolves in water to form its solution
called lime water.
Which among the following is (are) true about slaking of lime and the solution formed?

1. It is an endothermic reaction. 2. It is an exothermic reaction.

3. The pH of the resulting solution will be more than seven.
4. The pH of the resulting solution will be less than seven.
(a) 1 and 2 (b) 2 and 3 (c) 1 and 4 (d) 3 and 4

71. Identify the correct option from the given table which represents the type of reactions occurring in step 1
and step 2. Ans C

Option Endothermic Exothermic

a X ✓
b ✓ X
c ✓ ✓
d X X
72. It is important to balance the chemical equations to satisfy the law of conservation of mass. Which of the
following statements of the law is incorrect?
(a) The number of atoms of each elements remains the same, before and after a chemical reaction.
(b) The total mass of the elements present in the reactants is equal to the total mass of the elements presents
in the products.
(c) Mass can neither be created nor can it be destroyed in a chemical reaction.
(d) The chemical composition of the reactants is the same before and after the reaction.

73. Observe the given diagram and identify the correct statements.

(i) At anode, oxygen gas is evolved.

(ii) In the test tube covering the anode, the amount of gas collected is double than that of the gas collected in
the test tube covering the cathode.
(iii) At cathode, hydrogen gas is evolved. (iv) It is a decomposition reaction.
(a) (i), (iii) and (iv) (b) (i), (ii) and (iii)
(c) (iii) and (iv) (d) All the statements are correct.

74. Why is it important to balance a skeletal chemical equation?

(a) To verify the law of constant proportion. (b) To verify law of conservation of energy.
(c) To verify the law of conservation of momentum. (d) To verify the law of conservation of mass.

75. Marble statues are corroded or stained when they repeatedly come into contact with polluted rain water.
Identify the main reason.

(a) Polluted water is basic in nature hence it reacts with calcium carbonate.
(b) Decomposition of calcium carbonate to calcium oxide.
(c) Calcium carbonate dissolves in water to give calcium hydroxide.
(d) Polluted water is acidic in nature hence it reacts with calcium carbonate.

76. Which reaction is used in photography?

(a) CaO H2O → Ca(OH)2 + Heat (b) 2FeSO4 → heat → Fe2O3 + SO2 + SO3 Heat
(c) 2Cu + O2 → 2CuO (d) 2 AgBr →Sunlight → 2Ag + Br2
77. Which of the following is/are correct for a balanced chemical equation?

1. It is based on law of conservation of mass.

2. The physical states makes the chemical reaction less informative.
(a) Only 1 (b) Only 2 (c) Both 1 and 2 (d) Neither 1 nor 2

78. In the reaction of iron with copper sulphate solution:

CuSO4 + Fe → FeSO4 + Cu
Which option in the given table correctly represents the substance oxidised and the reducing agent?
Option Substance oxidised Reducing agent
(a) Fe Fe
(b) Fe FeSO4
(c) Cu Fe
(d) CuSO4 Fe

79. During the preparation of hydrogen chloride gas on a humid day, the gas is usually passed through the
guard tube containing calcium chloride. The role of calcium chloride taken in the guard tube is to:
(a) moisten the gas (b) absorb the evolved gas
(c) absorb Cl- ion from the evolved gas (d) absorb moisture from the gas

80. C6H12O6(aq) + 6O2(aq) → 6CO2(aq) + 6H2O(l)

The above reaction is a/an:
(a) endothermic reaction (b) displacement reaction (c) neutralisation reaction (d) exothermic reaction

81. Which one of the following is the example of precipitation reaction according to the given diagram?

(a) Cu(s)+ 2AgNO3(aq) → Cu(NO3)2(aq) + 2Ag(s) (b) CuCO3(s) → heat → CuO(s) CO2(g)
(c) N2(g) + 3H2(g) → 2NH3(g) (d) AgNO3(aq) + NaCl(aq) → AgCl(s) + NaNO3(aq)

82. When Ca(NO3)2 is heated, it gives CaO, NO2(g) and O2(g). The correct number of moles of Ca(NO3)2 ,
CaO, NO2(g) and O2(g) are present in the reaction are respectively
(a) 1, 2, 4, 1 (b) 2, 2, 4, 1 (c) 2, 1, 3, 2 (d) 2, 2, 2, 1

83. Which of the following statements about the reaction given below are incorrect?
2PbO(s) + C(s) → Pb(s) + CO2(g)
1. Lead is getting reduced. 2. Carbon dioxide is getting oxidised.
3. Carbon is getting oxidised. 4. Lead oxide is getting reduced.
(a) 1 and 2 (b) 3 and 4 (c) 1 and 3 (d) 2 and 4
84. Some types of chemical reactions are listed below.
- decomposition
- combination
- displacement
- double displacement
Which two of the following chemical reactions are of the SAME type?
P) AgNO3 + NaCl → AgCl + NaNO3 Q) Mg + 2HCI → MgCl + H2
R) CH +2O2 → CO₂+2H₂O S) 2KOH + H2SO4 → K2SO4 + H2O
(a) P and Q (b) Q and R (c) R and S (d) P and S

85. Galvanisation is a process of coating iron articles with a layer of zinc to prevent the iron from rusting.
The iron is protected even if the zinc coating is scratched and iron is exposed.
Which of the following is true about how zinc prevents the rusting of iron?
P) A galvanised iron article does not undergo oxidation.
Q) The zinc coating prevents contact of iron with air.
R) Zinc undergoes corrosion more easily than iron.
(a) only P (b) only Q (c) only P and Q (d) only Q and R

86. When hydrogen sulphide gas is passed through a blue solution of copper sulphate, a black precipitate of
copper sulphide is obtained and the sulphuric acid so formed remains in the solution. The reaction is an
example of-
(a) combination reaction (b) displacement reaction
(c) decomposition reaction (d) double decomposition reaction

87. The indication of chemical reaction in an activity is/are:

(a) change in state (b) change in colour (c) change in temperature (d) all of the above

88. A student added dilute HCl to Zn granules taken in a test tube as shown in the figure. The correct
observation would be:

(a) no change (b) evolution of gas

(c) Zn granules turned green (d) formation of a precipitate

89. Sodium sulphate and barium chloride mixed together as shown in the figure. Which colour substance is
formed in the test tube?

(a) White (b) Black (c) Green (d) Yellow

90. Identify the product which represents the solid state in the above reaction.

(a) Barium chloride (b) Barium sulphate (c) Sodium chloride (d) Sodium sulphate

91. The colour of the solution observed after 30 minutes of placing zinc metal to copper sulphate solution is
(a) Blue (b) Colourless (c) Dirty green (d) Reddish Brown

92. Which of the following are correctly matched?

1. C o m b i n a t i o n reaction - Formation of single product.
2. Decomposition reaction - Break down of single, entity.
3. T h e r m a l decomposition - Heat is used.
4. D i s p l a c e m e nt reaction - Based on reactivity series.
(a) 1, 2 and 3 (b) 1, 2 and 4 (c) 1, 3 and 4 (d) 1,2,3 and 4

93. What happens when a piece of zinc metal is added to copper sulphate solution?
(a) Decomposition reaction (b) Double displacement reaction
(c) Displacement reaction (d) Precipitation reaction

94. Three beakers labelled as P Q, and R each containing 25 ml of water were taken. A small
amount of NaOH, anhydrous CuSO4 and NaCl were added to the beakers P Q, and R
respectively. It was observed that there was an increase in the temperature of the solutions
contained in beakers P and Q, whereas in case of breaker R, the temperature of the solution
falls. Which one of the following statements(s) is (are

1. In beakers P and Q, exothermic process has occurred.

2. In beakers P and Q, endothermic process has occurred.
3. In beaker R, exothermic process has occurred.
4. In beaker R, endothermic process has occurred.
(a) Only 1 (b) Only 2 (c) 1 and 4 (d) 2 and 3
95. A small amount of copper power is heated as shown in the figure. Which reaction shows the above
process?

(a) 2Cu + O2 → 2CuO (b) CuO + H2 → Cu + H2O

(c) Cu + O2 → 2CuO (d) CuO + N2 → Cu + N2O

96 Match the items of Column I with the items of the Column II:

(a) (iv)-(B), (iii)-(D), (ii)-(A), (i)-(C) (b) (iii)-(A), (i)-(B), (iii)-(C), (iv)-(D)
(c) (ii)-(B), (iv)-(A), (i)-(C), (iii)-(D) (d) (i)-(D), (ii)-(C), (iii)-(A), (iv)-(B)

97. The balancing of chemical equation is based on:

(a) Law of conservation of energy (b) Law of conservation of mass
(c) Law of conservation of heat (d) None of these

98. What happens when dilute hydrochloric acid is added to iron fillings? Tick the correct answer:
(a) Hydrogen gas and iron chloride are produced. (b) Chlorine gas and iron hydroxide are produced.
(c) No reaction takes place. (d) Iron salt and water are produced

99. Identify the product which represents the solid state in the above reaction.

a) Barium chloride b) Barium sulphate c) Sodium chloride d) Sodium sulphate

100. The colour of the solution observed after 30 minutes of placing zinc metal to copper sulphate solution
is _______.
a) blue b) colourless c) dirty green d) reddish Brown
101. What happens when a piece of zinc metal is added to copper sulphate solution?
(a) Decomposition reaction (b) Double displacement reaction
(c) Displacement reaction (d) Precipitation reaction

102. Which of the following processes can not take place in the absence of oxygen?
(a) Combination (b) Combustion (c) Displacement (d) All of the above

103. In a combination how many products are formed?

(a) one only (b) two only (c) one or two only (d) number cannot be specified

104. Which of the following statement is true for chemical reaction given in following
figure.

(a) Yellow precipitate is formed (b) Soap is produced.

(c) Calcium Hydroxide turns milky (d) Calcium Hydroxide turns blue-black

105. The chemical reaction between potassium chloride and silver nitrate is given by the chemical equation.
AgNO3 + KCl → AgCl + KNO3
What can be inferred from the chemical equation?
(a) Silver nitrate and potassium chloride undergo a decomposition reaction to form silver chloride and
potassium nitrate.
(b) Silver nitrate and potassium chloride undergo a displacement reaction to form silver chloride and
potassium nitrate.
(c) Silver nitrate and potassium chloride undergo a combination reaction to form silver chloride and
potassium nitrate.
(d) Silver nitrate and potassium chloride undergo double displacement reaction to form silver chloride and
potassium nitrate

106. In the redox reaction

MnO2 + 4HCl → MnCl2 + 2H2O + Cl2
(a) MnO2 is reduced to MnCl2& HCl is oxidized to H2O
(b) MnO2 is reduced to MnCl2& HCl is oxidized to Cl2
(c) MnO2 is oxidized to MnCl2 & HCl is reduced to Cl2
(d) MnO2 is oxidized to MnCl2 & HCl is reduced to H2O

107. Which of the following is the correct observation of the reaction shown in the above set
up?

(a) Brown powder of Magnesium oxide is formed.

(b) Colourless gas which turns lime water milky is evolved.
(c) Magnesium ribbon burns with brilliant white light.
(d) Reddish brown gas with a smell of burning Sulphur has evolved

108. A substance which oxidizes itself and reduces other is known as

(a) Oxidising agent (b) reducing agent (c) Both (a) and (b) (d) None of these.

109. Dissolving sugar is an example of-

(a) Physical change (b) Chemical change (c) Redox Reaction (d) None of these.

110. Heat is evolved diving

(a) Endothermic Reaction (b) Displacement Reaction
(c) Combustion Reaction (d) Combination Reaction

111. The reaction between lead nitrate and potassium iodide present in aqueous
solutions is an example of
(a) Decomposition Reaction (b) Displacement Reaction
(c) Double Displacement Reaction (d) Neutralisation Reaction

112. What happens when dilute hydrochloric acid is added to iron filling? Tick
the correct answer
(a) Hydrogen gas and iron chloride are produced (b) Chlorine gas and iron hydroxide are produced
(c) No reaction takes place (d) Iron salt and water are produced

114. Which of the following statement about the given reaction is incorrect?
3Fe(s) + 4H2O(g) → Fe3O4 (s) + 4H2 (g)
(a) Iron metal is getting oxidized (b) Water is getting reduced
(c) Water is acting as a reducing agent (d) Water is acting as an oxidizing agent

115. In the double displacement reaction between aqueous potassium iodide and aqueous lead
nitrate, a yellow precipitate of lead iodide is formed. While performing the activity, if lead
nitrate is not available, which of the following can be used in place of lead nitrate?
(a) Lead sulphate (insoluble) (b) Lead acetate (c) Ammonium nitrate (d) Potassium sulphate
Questions - Reasoning based questions. These consist of two statements – Assertion (A) and Reason
(R). Answer these questions selecting the
appropriate option given below:
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
(e) Both A and R are false.

1. Assertion (A): Burning of natural gas is an endothermic process.

Reason (R): Methane gas combines with oxygen to produce carbon dioxide and water.

2. Assertion (A) : Photosynthesis is considered as an endothermic reaction.

Reason (R) : Energy gets released in the process of photosynthesis.

3. Assertion : Carbon dioxide turns lime water milky.

Reason : Carbon dioxide sullies the water.

4. Assertion : Corrosion of iron is a serious problem.

Reason : Every year an enormous amount of money is spent to replace damaged iron.

5. Assertion : The balancing of chemical equations is based on law of conservation of mass.

Reason : Total mass of reactants is equal to total mass of products.

6. Assertion(A) : Decomposition reactions are similar to combination reaction.

Reason (R): Both reactions need a catalyst to occur.

7. Assertion : When iron nail is dipped in copper sulphate solution, the iron nail becomes brownish in
colour and the blue colour of copper solution fade.
Reason : Equation representing this change is - Cu + FeSO4 → CuSO4 + Fe

8. Assertion : A chemical equation should be balanced.

Reason : Number of atoms of each element should be same on reactants as well as products side.

9. Assertion (A): Decomposition of vegetable matter into compost is an endothermic reaction.

Reason (R): Decomposition reaction involves breakdown of a single reactant into simpler products.

10. Assertion(A) : A chemical reaction becomes faster at higher temperatures.

Reason(R) : At higher temperatures, molecular motion becomes more rapid.

11. Assertion (A): White silver chloride turns grey in sunlight.

Reason (R): Decomposition of silver chloride in presence of sunlight takes place to form silver metal and
chlorine.

12. Assertion (A): when water is added to calcium oxide a large amount of heat is produced.
Reason (R): It is an endothermic reaction.

13. Assertion (A): The following chemical equation, 2C2H6 + 7/2 O2 → 4CO2 +3H2O
is a balanced chemical equation
Reason (R): In a balanced chemical equation, the total number of atoms of each element are equal on both
sides of the equation.

14. Assertion(A) : Silver chloride turns grey is sunlight.

Reason(R) : Silver is one of the least reactive metals.

15. Assertion(A) : Chemical equations can be made more informative.

Reason(R): We can write physical state of reactants and products, temperature and pressure, name of
catalyst used etc.

16. Assertion(A) : Equation C(s) + O2(g). → CO2(g) is an example of combination reaction.

Reason(R) : In the given above equation, carbon and oxygen react to give carbon dioxide.

17. Assertion(A): The following chemical equation, 2C2H6 + 7O2 → 4CO2 + 6H2O, is a balanced
chemical equation.
Reason(R) : In a balanced chemical equation, the total number of atoms of each element may or may not
equal on both side of the equation.

18. Assertion(A): Changing of colour of copper from reddish brown to black is an example of reduction.
Reason(B) : Hydrogen is removed.

19. Assertion(A) : Precipitation reactions produce insoluble salts.

Reason(R) : Precipitation reaction is a double decomposition reaction.

20. Assertion(A) : Fe2O3 + 2Al → Al2O3 +2Fe

The above chemical equation is an example of displacement reaction.
Reason(R) : Aluminium being more reactive than iron, displaces Fe from its oxide.

21. Assertion(A) : Chips manufacturers usually flush bags of chips with oxygen gas.
Reason(R) : It adds taste to chips. Ans C

22. Assertion (A): SO2 + 2H2S → 2H2O + 3S is a redox reaction.

Reason (R): In this reaction, oxidation of H2S to S and reduction of O2 to H2O takes place.

23. Assertion(A) : Corrosion of iron is commonly known as rusting.

Reason(R) : Corrosion of iron occurs in presence of water and air.

24. Assertion (A): Quicklime reacts vigorously with water releasing a large amount of heat.
Reason (R): A solution of quicklime is used for whitewashing walls.

25. Assertion(A) : A reducing agent is a substance which can either accept electron.
Reason(R) : A substance which helps in oxidation is known as reducing agent.

26. Assertion (A) : Decomposition of vegetable matter into compost is an example of exothermic reactions.
Reason (R) : Exothermic reaction are those reactions in which heat is evolved.

27. Assertion (A): Rusting of iron metal is the most common form of corrosion.
Reason (R): The effect of rusting of iron can be reversed if they are left open in sunlight.

28. Assertion (A) : When HCl is added to zinc granules, a chemical reaction occurs.
Reason (R) : Evolution of a gas and change in colour indicate that the chemical reaction is taking place.

29. Assertion (A) : Brown fumes are produced when lead nitrate is heated.
Reason (R) : Nitrogen dioxide gas is produced as a by product due to the decomposition of lead nitrate.

30. Assertion (A) : The main product formed by reaction of Zinc with Sodium Hydroxide is Sodium Zincate
Reason (R) : Zinc cannot displaces Sodium from its solution.

31. Assertion (A): PbO + C → Pb + CO is a reduction reaction.

Reason(R): PbO is reduced and C is oxidized.

32. Assertion (A) : Silver bromide is used in photography.

Reason (R): Silver bromide is photosensitive. It decomposes and is converted into metallic silver grains
when light is incident on it.
33. Assertion (A): Zinc oxide can be reduced to zinc metal on heating with carbon.
Reason (R): Carbon is less reactive than zinc.

34. Assertion (A): Rusting of Iron is endothermic in nature.

Reason (R): As the reaction is slow, the release of heat is barely evident.
35. Assertion(A): Silver bromide decomposition is used in black and white photography.
Reason(R): Light provides energy for this exothermic reaction

SECTION – B
The following questions are very short answer type and carry 2 marks each.

1. Observe the given figure and answer the questions that follow:

(i) Identify the gas X .

(ii) Write the chemical reaction involved.
(iii) Which type of chemical reaction is taking place?
(iv) is it an exothermic reaction or an endothermic reaction?

2. Name the gas which is usually produced when dil. sulphuric acid reacts with a metal. Illustrate it with an
example. How will you test the evolution of this gas.

3. Explain why sodium hydroxide solution cannot be kept in aluminium containers ? Write equation for the
reaction that may take for the same.

4. In one method of rust prevention, the iron is not coated with anything. Name the method and define it.

5. A green salt on heating decomposes to produce a colourless suffocating gas and leaves behind a reddish
brown residue. Name the salt and write the decomposition reaction.

6. In one method of rust prevention, the iron is not coated with anything. Name the method and define it.

7. The following reaction takes place when aluminium powder is heated with MnO 2 :
3MnO2(s) + 4Al(s) → 3Mn(l) + 2Al2O3(l) + Heat
(i) Is aluminium getting reduced?
(ii) Is MnO2 getting oxidised?

8. What would you observe when zinc is added to a solution of iron(II) sulphate ? Write the chemical
reaction that takes place.

9. You might have noted that when copper powder is heated in a China dish, the surface of copper powder
becomes coated with a black colour substance.
(i) How has this black-coloured substance formed?
(ii) What is that black substance?
(iii) Write the chemical equation of the reaction that takes place.
10. (i) Fe + CuSO4 → FeSO4+ Cu
(iii) Cu+ FeSO4 → CuSO2 + Fe
Which of the above to reaction will take place and why?

11. A substance X , which is an oxide of a metal is used intensively in the cement industry. This element is
present in bones also. On treatment with water it forms a solution which turns red litmus blue. Identify X
and also write the chemical reactions involved.

12. Identify the oxidising agent in the following reactions:

(i) Pb3O4 + 8HCl → 3PbCl2 + Cl + H2O
(ii) 2Mg + O2 → 2MgO

13. Give reasons for the following :

(a) We can store copper sulphate solution in silver vessel but not silver nitrate solution in a copper vessel.
(b) Food cans are coated with tin rather than zinc.

14. Write the balanced chemical equations for the following reactions and identify the type of reaction in
each case.
(i) Nitrogen gas is treated with hydrogen gas in the presence of a catalyst at 773K to form ammonia gas.
(ii) Ethene is burnt in the presence of oxygen to form carbon dioxide, water and releases heat and light.

15. What happens when hydrogen gas is passed over the heated copper oxide? Write the chemical equation
involved in this reaction.

16. In the arrangement shown below there are three test tubes marked A, B and C. Few clean iron nails are
placed in these tubes. Water is poured in test tube A, boiled distilled water and 1 mL of oil are poured in test
tube B and anhydrous calcium chloride is added in test tube C.

What are the two observations that can be observed after a few days from the given arrangement?

17. With an example differentiate between combination and decomposition reaction?

18. List any two observations when a highly reactive metal is dropped in water.

19. What is wrong with the following equation?

Mg + O ➝ MgO
Identify the mistake and balance the equation.

20. AgNO3(aq) + NaCl(aq) → AgCl(s)4↓ + NaNO3(aq)

FeS + H2SO4 → FeSO4 + H2S↑
Consider the above mentioned two chemical equations with two different kinds of arrows (↑and ↓) along
with product. What do these two different arrows indicate?

21 “We need to balance a skeletal chemical equation.” Give reason to justify the statement.
22. What do you mean by exothermic and endothermic reactions? Give examples.

23. Identify the reducing agent in the following reactions:

(i) H2O + F2 → 2HF + HOF
(ii) Fe2O3 + 3CO → 2Fe + 3CO2

24. Which among the following changes are exothermic or endothermic in nature?
(i) Decomposition of ferrous sulphate.
(ii) Dilution of sulphuric acid.
(iii) Dissolution of sodium hydroxide in water.
(iv) Dissolution of ammonium chloride in water.

25. Dil. HCl is added to Zn granules.” How will you prove that chemical change has taken place
here? Support your response with two arguments.

26. Write one chemical equation each for decomposition reaction where energy is supplied in the form of
heat and light energy.

27. A solution of potassium chloride when mixed with silver nitrate solution, an insoluble white substance is
formed. Write the chemical reaction involved and also mention the type of chemical reaction?

28. When Ferrous sulphate is heated, the evolution of a gas having a characteristic Odour of burning
Sulphur. Write the chemical reaction involved and identify the type of reaction.

29. What happens when zinc granules are treated with a dilute solution of (i) Hydrochloric acid (ii) Sodium
hydroxide, also write the chemical equations.

30. i) Write the balanced chemical equation for the reaction that is prevented by storing potassium metal
under kerosene.
ii) Identify the type of chemical reaction that is prevented.

31. Dil. HCl is added to Zn granules.” How will you prove that chemical change has taken place here?
Support your response with two arguments.

32. A clear solution of slaked lime is made by dissolving Ca(OH)2 in an excess of water. This solution is left
exposed to air. The solution slowly goes milky as a faint white precipitate forms. Explain why a faint white
precipitate forms, support your response with the help of a chemical equation.

SECTION – C
The following questions are short answer type and carry 3 marks each.
1. Identify the type of reactions taking place in each of the following cases and write the balanced chemical
equation for the reactions.
(i) Zinc reacts with silver nitrate to produce zinc nitrate and silver.
(ii) Potassium iodide reacts with lead nitrate to produce potassium nitrate and lead iodide.

2. Explain the following chemical changes, giving one example in each case :
(i) Displacement or substitution,
(ii) Dissociation,
(iii) Isomerisation reaction.

3. Study the figure given below and answer the following questions :
(a) Name the process depicted in the diagram.
(b) Write the composition of the anode and the cathode.
(c) Write the balanced chemical equation of the reaction taking place in this case

4. State which of the following chemical reactions will take place or not, giving suitable reason for each :
(i) Zn(s) + CuSO4(aq) → ZnSO4(aq) + Cu(s)
(ii) Fe(s) + ZnSO4(aq) → FeSO4(aq) + Zn(s)
(iii) Zn(s) + FeSO4(aq) → ZnSO4(aq) + Fe(s)

5. How does rusting take place ? Write the conditions necessary for rusting to take place.

6. A shining metal M , of burning gives a dazzling white flame and changes to a white powder N .
(a) Identify M and N .
(b) Represent the above reaction in the form of a balanced chemical equation.
(c) Does M undergo oxidation or reduction in this reaction ? Justify.

7. Name three chemical reactions in which heat is evolved and three chemical reactions in which heat is
absorbed.

8. Identify the type of each of the following reactions stating reason for your answers :
(a) Fe2O3 + 2Al → Al2O3 + 2Fe + heat
(b) Pb(NO3)2 + 2Kl → Pbl2 + 2KNO3
(c) ZnCO3 →heat→ ZnO + CO2

9. Lead nitrate solution is added to a test tube containing potassium iodide solution.
(a) Write the name and colour of the compound precipitated.
(b) Write the balanced chemical equation for the reaction involved.
(c) Name the type of this reaction justifying your answer.

10. i) Write the essential condition for the following reaction to take place: 2AgBr → 2Ag + Br2
Write one application of this reaction.
(ii) Complete the following chemical equation of a chemical reaction:
2FeSO4 → Fe3O4 + _________ + _________ Heat
(iii) What happens when water is added to quick lime? Write chemical equation.

11. Write and balance the following questions presented to you as written statements :
(i) Magnesium carbonate plus hydrochloric acid produces magnesium chloride plus water plus carbon
dioxide gas.
(ii) Aluminium plus chlorine gas produces aluminium trichloride.
(iii) Nitrogen plus hydrogen produces ammonia.

12. Give chemical explanation for evolution and absorption of heat in a chemical reaction.
Consider the following diagram :
(i) Identify ‘X’ and ‘Y’.
(ii) What type of reaction is it?
(iii) Write a balanced chemical equation.
(iv) Explain why is it also called a double displacement reaction?

13. Name the type of chemical reaction represented by the following equation.
i) CaCO3(s) → heat→ CaO(s) + CO2(g)
ii) CaO(s) + H2O(l) → Ca(OH)2(aq)
iii) Zn(s) + H2SO4(aq) → ZnSO4 + H2(g)

14. Give chemical explanation for evolution and absorption of heat in a chemical reaction.

15. Observe the given figure and answer the following questions:

(i) Which gas is evolved?

(ii) How will you test for the presence of gas evolved?
(iii) What will happen to the lime water?
(iv) What happens when the gas is passed for a longer time

16. Identify the substances that are oxidised and that are reduced in the following reactions :
(i) ZnO + C → Zn + CO
(ii) CuO + H2 → Cu + H2O
(iii) MnO2+ 4HCl → MnCl2 + 2H2O + Cl2

17. What does a balanced chemical equation convey ?

18. Justify with the help of an example that displacement reaction is also a redox reaction.

19. What is an oxidizing agent ? What happens when an oxidizing agent is added to propanol ? Explain with
the help of a chemical equation.
20. In an experiment 20 g of zinc (A) was reacted with 20 g of iodine (B) in a 250 ml beaker containing 50
ml water. Reaction proceeded with evolution of heat and at the end, reaction mixture did not give any colour
on adding starch solution, but some zinc was found settling at the bottom.
Zn(s) + I2(s) → 2ZnI(s) + heat
(i) Is the reaction endothermic or exothermic ?
(ii) Out of the two reactants, Zn(s) and I2(s), which one is left unreacted ? Why?
(iii) How much of (A) and (B) should he taken so that no reactant is left out at the end of the reaction ?

21. When hydrogen sulphide gas is passed through a blue solution of copper sulphate, the colour of the
solution fades and a black precipitate is obtained.
(a) Name the type of reaction mentioned above.
(b) Why does the colour of the solution fade away ?
(c) Write the chemical name of the black precipitate formed.

22. In the electrolysis of water :

(a) Name the gases liberated at anode and cathode.
(b) Why is it that the volume of gas collected on one electrode is two times that on the other electrode?
(c) What would happen if dil. H2SO4 is not added to water ?

23. Name the type of chemical reaction represented by the following equation.
(i) CaCO3(s) → heat → CaO(s) + CO2(g)
(ii) CaO(s) + H2O(l) → Ca(OH)2(aq)
(iii) H2SO4 (aq) + Zn(s) → ZnSO4 (aq) + H2 (g)

24. Design an activity to show a decomposition reaction in which light is used to decompose a reactant.
Write chemical equation for the reaction and state its one use

25. Write an experiment to show that copper does not react with dilute HCl.

26. What is a thermochemical equation ? Give two examples.

27. You are given a white solid which is calcium carbonate, CaCO3.

(i) What happens to the white solid after heating?

(ii) What will you observe in the lime water during the heating process?
(iii) Write the reactions involved.

28. What is meant by skeletal type chemical equation? What does it represents? Using the equation for
electrolytic decomposition of water, differentiate between a skeletal chemical equation and a balanced
chemical equation.

29. In an experimental set-up, 10 mL of copper sulphate is taken in both the test tubes A and B. Iron nails are
dipped in test tube B for about 20 minutes. The given figure shows the comparison of iron nails and copper
sulphate solutions before and after the reaction. Observe the given figure and answer the questions that
follow:
(i) What changes in the colour of iron nail and copper sulphate solution do you observe after keeping the
iron nail dipped in copper sulphate solution for about 20 minutes?
(ii) Why does the blue colour of copper sulphate fade by adding iron nail in it?
(iii) Write the chemical reaction involved. Name the type of reaction in the above activity.

30. Identify the compound X on the basis of the reactions given below. Also, write the name and chemical
formulae of A, B and C.

31. 1 g of copper powder was taken in a China dish and heated. What change takes place on heating ? When
hydrogen gas is passed over this heated substance, a visible change is seen in it, Give the chemical equations
of reactions, the name and the colour of the products formed in each case.

32. What is an oxidation reaction? Give an example of oxidation reaction. Is oxidation an exothermic or an
endothermic reaction?

33 . Write one example for each of decomposition reaction carried out with help of
(i) Electricity (ii) Heat (iii) Light

34. a) Classify the following reactions into different types.

(b) Which of the above reaction(s) is/are precipitation reaction(s)? Why is a reaction called precipitation
reaction?

35. A magnesium ribbon is burnt in oxygen to give a white compound X accompanied by emission of light.
If the burning ribbon is now placed in an atmosphere of nitrogen, it continues to burn and forms a compound
Y.
(a) Write the chemical formulae of X and Y.
(b) Write a balanced chemical equation, when X is dissolved in water.
(c) Why should a magnesium ribbon be cleaned before burning in air?
36. The given set up shows the electrolysis of water taking place.

(a) Identify the gases evolved at cathode and anode.

(b) Why is the amount of gas collected in one of the test tubes double the amount in the other? Name this
gas.
(c) How will you test the evolved gases?

37.

Identify the types of reaction mentioned above in (i) and (ii). Give one example for
Each type in the form of a balanced chemical equation.

38. A metal X is obtained from its chloride salt by exposure to sunlight.

(a) In which section of the reactivity series of metals- top, middle or bottom, is it likely to be placed? Justify
your answer.
(b) Identify the type of reaction the chloride salt of metal X undergoes on exposure to sunlight

39. The given reaction shows one of the processes to extract the metals like Iron and Manganese.
MnO₂ (s) + Al(s) → Mn(l) + Al₂O₃(s) + Heat
a) Give reason why the above reaction is known as a thermite reaction.
b) Identify the substance oxidised and reduced in the above reaction.
c) Give a reason why Aluminium is preferably used in thermite reactions.

SECTION – D
The following questions are long answer type and carry 5 marks each.

1.(i) Explain the following terms with one example each:

(a) Corrosion
(b) Rancidity
(ii) Explain two ways by which food industries prevent rancidity.

2. (i) Balance the following chemical equations:

(a) NaOH + H2SO4 →Na2SO4 + H2O
(b) PbO + C → Pb + CO2
(c) Fe2O3 + Al → Al2O3 + Fe + Heat
(ii) Write the balanced chemical equations for the following reactions:
(a) Barium chloride + Potassium sulphate → Barium sulphate + Potassium chloride
(b) Zinc + Silver nitrate → Zinc nitrate + Silver

3. i) Design an activity to show the conditions needed for iron nails to rust.
(ii) Why do we apply paint on iron articles ?

4. A student dropped few pieces of marble in dilute hydrochloric acid, contained in a test tube. The evolved
gas was then passed through lime water. What change would be observed in lime water ? What will happen
if excess of gas is passed through lime water ? Write balanced chemical equations for all the changes
observed.

5. A) Write the chemical equation of the reaction in which the following changes have taken place with an
example of each:
(i) Change in colour
(ii) Change in temperature
B) Identify the substances that are oxidised and that are reduced in the following reactions : (3)
(i) ZnO + C → Zn + CO
(ii) CuO + H2 → Cu + H2O
(iii) MnO2 + 4HCl → MnCl2 + 2H2O + Cl2

6. Translate the following statements into chemical equations and balance them:.
(i) Nitrogen gas is treated with hydrogen gas in the presence of a catalyst at 773K to form ammonia gas.
(ii) Ethene is burnt in the presence of oxygen to form carbon dioxide, water and releases heat and light.
(iii) Lead nitrate reacts with sulphuric acid to form a precipitate of lead sulphate and nitric acid.
(iv) Magnesium burns in the presence of nitrogen to form magnesium nitride.
(v) Aluminium metal strip is added in hydrochloric acid to produce aluminium chloride and hydrogen gas.

7. A) Identify the type of each of the following reactions stating reason for your answers :
(i) Fe2O3 + 2Al → Al2O3 + 3Fe + heat
(ii) Pb(NO3)2 + 2Kl → Pbl2 + 2KNO3
(iii) ZnCO3 ∆ ZnO + CO2
B)What is the difference between the following two types of reactions ?
(i) CaO + H2O → Ca(OH)2
(ii) Mg + 2HCl → MgCl2 + H2

8. (a) Define corrosion.

(b) What is corrosion of iron called ?
(c) How will you recognise the corrosion of silver ?
(d) Why corrosion of iron is a serious problem ?
(e) How can we prevent corrosion of iron ?

SECTION – E
Questions are case – based/data -based questions with 2 to 3 short sub – parts. Internal
choice is provided in one of these sub-parts.

1. Oxidation is the process of gaining of oxygen or losing of hydrogen. Reduction is the process of losing of
oxygen or gaining of hydrogen. The substance which undergoes oxidation is the reducing agent while the
substance which undergoes reduction is known as the oxidising agent. Oxidation and reduction always take
place together and these type of reactions are known as redox reactions. Some of the examples of redox
reactions are given below :
(a) Pb3O4 + 8HCl → 3PbCl2 + Cl2 + 4H2O
(b) 2Mg + O2 → 2MgO
(c) CuSO4 + Zn → Cu + ZnSO4
 (d) V2O5 + 5Ca → 2V + 5CaO
(e) 3Fe + 4H2O → Fe2O4 + 4H2
(f) CuO + H2 → Cu + H2O
(i) Give two examples of oxidation reaction from your everyday life.
(ii) Write the oxidising agent in the reaction a and b.
OR
(iii) Out of oxidation and reduction, which reaction takes place at anode?

2. There are different types of chemical reactions occurring around us or being carried out for the benefit of
mankind, e.g. combination reactions, decomposition reactions, displacement reactions, precipitation
reactions, reduction-oxidation (redox) reactions, photochemical reactions etc.
Now, answer the following questions :
(i) Combustion of coke is a combination reaction. CO2 is not a pollutant. Then, why is combustion of coke
harmful?
(ii) Which reaction followed by two combination reactions are involved in white wash of walls?
(iii) Give one use of tin plating in daily life.
OR
(iv) How photochemical reactions have played an important in photography?

3. When two or more substances react and form some new substance, it is called a chemical reaction.
Chemical equation is represented in terms of symbols, molecular formulas, moles, states, etc. As we know,
all chemical reaction obeys law of chemical combination. Therefore, chemical reactions need to be balanced.
It is done by hit and trial method. The chemical reactions can be classified into different types such as
combination reaction, decomposition reaction, displacement reaction, double displacement reaction. The
reactions take place in solution is precipitation reactions and neutralisation reactions.

(i) Define a chemical equation.

(ii) Which law is followed by all chemical reactions?
(iii) Name four types of chemical reactions.
OR
(iv) Give example of precipitation reactions.

4. After seeing the image answer the following questions.

(i) What was the colour of the crystals before heating and after heating?
(ii) Write the chemical equation for the reaction.
(iii) Which pungent smelling gas is evolved during the reaction ? What is the nature of this gas?
OR
(iv) Write the name of the solid substance formed.

5. When a metal is attacked by substances around it such as moisture, acids, etc., it is said to corrode, and
this process is called corrosion. The black coating on silver, green coating on copper and reddish-brown
powder on iron surface are some examples of corrosion.
Answer the following:
(i) What is the name given to the corrosion of iron?
(ii) What is the formula of green colour coating on copper?
(iii) Name two methods to prevent corrosion of iron.
OR
(iv) Is corrosion a redox reaction?

6. Electrolysis of water is a popular method used for different applications in various industries. The
electrolysis of water is mainly carried out to yield pure hydrogen and oxygen gases. It involves passing an
electric current through the water which results in decomposition of water into hydrogen and oxygen. Pure
water is a poor conductor of electricity. Sulphuric acid is added to the water so that the conductance of water
increases which makes the reaction faster. The setup for electrolysis of water is given below: The number of
hydrogen molecules produced in electrolysis is twice the number of oxygen molecules. Also, hydrogen is
double in volume than oxygen.

(i) Name the gases evolved at cathode and anode respectively. Why is volume of one gas collected at one
electrode is double of anode?
(ii) How will you test the gas evolved at cathode and at anode?
OR
(iv) Write the chemical equation for electrolysis of water. Why are few drops of H 2SO4 added to pure water?

7. A student prepared oxygen in a lab by catalytic decomposition of potassium chlorate (KClO 3) as shown
in the figure. Decomposition of potassium chlorate gives potassium chloride (KCl) and oxygen (O 2) . The
following reaction takes place :
KClO3(s) → KCl(s) + O2(g)
(i) How many moles of KClO3 are required to 2.4 moles of O2 ?
(ii) Name the element which is reduced in the given reaction.
(iii) How many moles of KClO3 give 3 moles of oxygen?
OR
(iv) What is the oxidation state of chlorine in potassium chlorate?

8. When a metal is attacked by substances around it such as moisture, acids, etc., it is said to corrode, and
this process is called corrosion. The black coating on silver, green coating on copper and reddish-brown
powder on iron surface are some examples of corrosion.
Answer the following:
(i) What is the name given to the corrosion of iron?
(ii) What is the formula of green colour coating on copper?
(iii) Name two methods to prevent corrosion of iron.
OR
(iv) Is corrosion a redox reaction?

9. When two or more substances react and form some new substance, it is called a chemical reaction.
Chemical equation is represented in terms of symbols, molecular formulas, moles, states, etc. As we know,
all chemical reaction obeys law of chemical combination. Therefore, chemical reactions need to be balanced.
It is done by hit and trial method. The chemical reactions can be classified into different types such as
combination reaction, decomposition reaction, displacement reaction, double displacement reaction. The
reactions take place in solution is precipitation reactions and neutralisation reactions.
(i) Define a chemical equation.
(ii) Which law is followed by all chemical reactions?
(iii) Name four types of chemical reactions.

(iv) Give example of precipitation reactions.

10. When a silvery grey powder of a solid (A) is mixed with a powder of solid (B) no reaction occurs. But if
the mixture is ignited and lighted using magnesium ribbon a reaction occurs with evolution of large amount
of heat forming product (C) which settles down as liquid metal and the solid product (D) formed floats on
the liquid (C) in solid form reacts with moisture to form rust. The amount of heat generated during the
reaction is so high that the reaction is used in welding of electric conductors, joints in railway tracks.
Answer the following:
(i) Identify (A), (B), (C) and (D). Write the balanced chemical equation for the reaction. Name the type of
reaction.
(ii) If (A) reacts with air on heating that will be the nature of oxide formed?
OR
(iv) Does oxide of (A) react with aqueous NaOH and/or HCl. Give balanced chemical equations

11. Corrosion is the phenomenon of deterioration of surface of metal in presence of air and moisture. It is a
natural process and in the presence of a moist atmosphere, chemically active metals get corroded. This is
oxidation reaction. Rusting is the process where iron corrodes due to exposure to the atmosphere. The main
circumstance of corrosion occurs with iron because it is a structural material in construction, bridges,
buildings, rail transport, ships, etc. Aluminium is also an important structural metal, but even aluminium
undergoes oxidation reactions. However, aluminium doesn’t corrode or oxidize as rapidly as its reactivity
suggests. An alloy of aluminium or any other metal like magnesium can make aluminium stronger and
harder. Copper (Cu) corrodes and forms a basic green carbonate and lead corrodes to form a white lead
oxide or carbonate.

(i) What is rusting?

(ii) Which two metals do not corrode easily?
(iii) List two properties of alloys.
OR
(iv) What is the effect of corrosion on electrical conductivity ?
12. In a balanced chemical reaction, equal number of atoms are present on both sides of reaction. A balanced
chemical reaction is based on law of conservation of mass which means that total mass of reactants and
products participating in a reaction must be equal. For example, a balanced chemical equation of burning of
magnesium in oxygen to form magnesium oxide is written as: 2Mg+O2 → 2MgO
The mass of reactants (2 x 24 + 32 = 80) is equal to the mass of products [2 x (24 +16) = 80].
Answer the following:
(i) In a reaction, 35 g of reactant, PQ breaks down into 20 g of product, P and an unknown amount of
product, Q. Find the amount of product Q.
(ii) The solid mercury (II) oxide is heated, and liquid mercury and oxygen gas are produced. Mention
balanced chemical reaction.
(iii) Which laws are satisfied by a balanced chemical equation?
OR
iv) In the given chemical reaction, 2C6H6(I) +15O2(g) → mCO2(g) + H2O(1)
Find the values of m and n respectively.

13. Rishabh wanted to study displacement reactions. He knows that he needs a metal and a salt solution of a
different metal. So, he takes two tubes T1 and T2, out of which in T1, he placed a copper wire in iron
sulphate solution and in T2, he placed an iron nail in copper sulphate solution as shown below:

(i) Based on the given information, which test tube will undergo displacement reaction? Also, write the
chemical reaction occurring in that test tube.
(ii) State the changes observed in T1 and T2.
OR
(iii) What will happen (a) when zinc wire is used in place of copper wire in T1 and (b) when silver nitrate is
used in place of iron sulphate in T1?

14. When the fats and oil present in the food material get oxidized by the oxygen (of air), their oxidation
products have unpleasant smells and tastes. Due to this taste of food material containing fats and oil change
and become very unpleasant. The condition produced by aerial oxidation of fats and oils in food marked by
unpleasant smell and taste is called rancidity. Rancidity spoils the food material prepared in the fats and oils
which have been kept for a considerable time and makes them unfit for eating.
The development of rancidity in food can be prevented in the following ways-
i. Rancidity can be prevented by adding an antioxidant to foods containing fats and oils.
ii. Rancidity can be prevented by packaging fat and oil-containing food in Nitrogen gas.
iii. Rancidity can be prevented by keeping food in a refrigerator.

(i) What do you understand by oxidation?

(ii) How does the food become rancid?
(iii) How can we prevent the rancidity of food?
OR
iv) Which type of food material gets spoiled by the phenomenon of rancidity?

15. Two students decided to investigate the effect of water and air on iron object under identical
experimental conditions. They measured the mass of each object before placing it partially immersed in 10
ml of water. After a few days, the object were removed, dried and their masses were measured. The table
shows their results.

(a) What might be the reason for the varied observations of the two students?
(b) i) In another set up the students coated iron nails with zinc metal and noted that, iron nails coated with
zinc prevents rusting. They also observed that zinc initially acts as a physical barrier, but an extra advantage
of using zinc is that it continues to prevent rusting even if the layer of zinc is damaged. Name this process of
rust prevention and give any two other methods to prevent rusting.
OR
ii) In which of the following applications of Iron, rusting will occur most?
Support your answer with valid reason.

A - Iron Bucket electroplated with Zinc

B - Electricity cables having iron wires covered with aluminium
C - Iron hinges on a gate
D - Painted iron fence

16. Read the text carefully and answer the questions:

In a redox reaction, both oxidation, as well as reduction, takes place together, oxidation involves loss of
electrons while reduction involves the gain of electrons. The redox- reaction may involve a combination of
atoms and molecules, displacement of metals, or non-metals.
Example: CuSO4 + Zn → ZnSO4 + Cu displacement of Cu metal from its compound.
Answer the following:
(i) In the below equation, which gets reduced? CuSO 4+ Zn → ZnSO4 + Cu
(ii) The oxidising agent generally loses or gains an electron.
(iii) Identify the oxidising agent and reducing agent in the above reaction.
CuSO4 + Zn → ZnSO4 + Cu
OR
iv) Identify the type of given reaction. CuSO4+ Zn→ ZnSO4 + Cu

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