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Chemical Reactions and Equations

Exemplar problems MCQs part 2

Question 1: 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

1. (i) only
2. (ii) only
3. (iv) only
4. (ii) and (iv)

Answer: (d) (ii) and (iv)

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Question 2: Electrolysis of water is a decomposition reaction. The mole ratio of hydrogen and oxygen gases liberated during electrolysis of water is

1. 1 : 1
2. 2 : 1
3. 4 : 1
4. 1 : 2

Answer: (b) 2:1

Question 3: Which of the following is (are) an endothermic process(es)?

1. Dilution of sulphuric acid
2. Sublimation of dry ice
3. Condensation of water vapours
4. Evaporation of water

1. (i) and (iii)
2. (ii) only
3. (iii) only
4. (ii) and (iv)

Answer: (d) (ii) and (iv)

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Question 4: 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?

1. Lead sulphate (insoluble)
2. Lead acetate
3. Ammonium nitrate
4. Potassium sulphate

Answer: (b) Lead acetate

Question 5: Which of the following gases can be used for storage of fresh sample of an oil for a long time?

1. Carbon dioxide or oxygen
2. Nitrogen or oxygen
3. Carbon dioxide or helium
4. Helium or nitrogen

Answer: (d) Helium or nitrogen

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Question 6: The following reaction is used for the preparation of oxygen gas in the laboratory

2KClO₃ (s) + heat + catalyst ⇨ 2KCl + 3O₂

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

1. It is a decomposition reaction and endothermic in nature
2. It is a combination reaction
3. It is a decomposition reaction and accompanied by release of heat
4. It is a photochemical decomposition reaction and exothermic in nature

Answer: (a) It is a decomposition reaction and endothermic in nature

Question 7: In which of the following chemical equations, the abbreviations represent the correct states of the reactants and products involved at reaction temperature?

1. 2H₂ (l) + O₂ (l) ⇨ 2H₂O (g)
2. 2H₂ (g) + O₂ (l) ⇨ 2H₂O (g)
3. 2H₂ (g) + O₂ (g) ⇨ 2H₂O (l)
4. 2H₂ (g) + O₂ (g) ⇨ 2H₂O (g)

Answer: (c) 2H₂ (g) + O₂ (g) ⇨ 2H₂O (l)

Question 8: Which of the following are combination reactions?

1. 2KClO₃ ⇨ 2KCl + 3O₂
2. MgO + H₂O ⇨ Mg(OH)₂
3. 4Al + 3O₂ ⇨ 2Al₂O₃
4. Zn + FeSO₄ ⇨ ZnSO₄ + Fe

1. (i) and (iii)
2. (iii) and (iv)
3. (ii) and (iv)
4. (ii) and (iii)

Answer: (d) (ii) and (iii)

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