Question 11: 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?
Answer: (d) (ii) and (iv)
Explanation: Barium and Ammonia are displacing each other from their respective salts. So, statement (iv) is true. Barium sulphate appears as precipitate at the end of this reaction. So, statement (ii) is true.
Question 12: Electrolysis of water is a decomposition reaction. The mole ratio of hydrogen and oxygen gases liberated during electrolysis of water is
Answer: (b) 2:1
Explanation: Water molecule is composed of two atoms of hydrogen and one atom of oxygen.
Question 13: Which of the following is (are) an endothermic process(es)?
Answer: (d) (ii) and (iv)
Explanation: Heat needs to be supplied for these processes.
Question 14: 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?
Answer: (b) Lead acetate
Explanation: We need to make lead iodide, so we need a lead compound as reactant. This condition rules out options (c) and (d). Compounds taking place in double displacement reaction should be soluble in water and should break into their ions in aqueous solution.
Question 15: Which of the following gases can be used for storage of fresh sample of an oil for a long time?
Answer: (d) Helium or nitrogen
Explanation: Carbon dioxide and oxygen are reactive gases. So, options (a), (b) and (c) can be easily ruled out. Helium is an inert gas, while nitrogen is almost inert in nature.
Question 16: 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?
Answer: (a) It is a decomposition reaction and endothermic in nature
Explanation: Potassium chlorate decomposes to give potassium chloride and oxygen. Heat is supplied in this reaction. So, option (a) is correct.
Question 17: In which of the following chemical equations, the abbreviations represent the correct states of the reactants and products involved at reaction temperature?
Answer: (c) 2H2 (g) + O2 (g) ⇨ 2H2O (l)
Explanation: Hydrogen and oxygen are available as gases on room temperature, while water is a liquid at room temperature.
Question 18: Which of the following are combination reactions?
Answer: (d) (ii) and (iii)
Explanation: A single substance is formed at the end of each of these reactions.
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