Chemistry 9th Chap 10 : Topic 7 - Maryam Publications

Chemistry Chapter 10 : Topic 7

Reactions of Bases

1 / 18

A student adds a few drops of hydrochloric acid (HCl) to a solution of sodium hydroxide (NaOH). The reaction results in formation of salt and water, and the solution becomes neutral. What type of reaction is this?

A) Redox reaction

B) Displacement reaction

C) Neutralization reaction

D) Decomposition reaction

2 / 18

When a strong base like sodium hydroxide reacts completely with a strong acid like sulfuric acid, the resulting solution shows no acidic or basic properties. What does this confirm about bases?

A) Bases neutralize acids to form salt and water.

B) Bases increase acidity of solutions.

C) Bases decompose acids into elements.

D) Bases always form gases with acids.

3 / 18

A white solid ammonium chloride (NH₄Cl) is heated with sodium hydroxide solution. A pungent gas is produced which turns moist red litmus paper blue. What does this reaction indicate about bases?

A) Bases form precipitates with all salts.

B) Bases produce oxygen gas with salts.

C) Bases neutralize salts into acids.

D) Bases react with ammonium salts to release ammonia gas.

4 / 18

During a laboratory experiment, a student adds sodium hydroxide to ammonium chloride solution. A strong smelling gas evolves. Which conclusion is most appropriate?

A) Bases always produce carbon dioxide gas.

B) Bases convert salts into metals.

C) Bases decompose acids into hydrogen gas.

D) Bases react with ammonium salts producing ammonia gas.

5 / 18

A teacher explains that when ammonium sulfate is treated with a base, ammonia gas is released. Which property of bases is being demonstrated?

A) Bases react with ammonium salts to liberate ammonia.

B) Bases are corrosive in all conditions.

C) Bases change into acids on heating.

D) Bases form insoluble salts only.

6 / 18

A solution of sodium hydroxide is added to hydrochloric acid in equal amounts. The temperature of the mixture increases. What does this temperature change indicate?

A) Formation of gas bubbles only

B) Exothermic neutralization reaction

C) Endothermic decomposition of acid

D) Physical mixing without reaction

7 / 18

A gas produced in a reaction between a base and an ammonium salt turns damp red litmus paper blue and has a sharp smell. What is this gas?

A) Carbon dioxide

B) Oxygen

C) Hydrogen

D) Ammonia

8 / 18

Which observation correctly supports the reaction between a base and an acid?

A) Formation of a colored precipitate

B) Formation of salt and water

C) Evolution of oxygen gas

D) Production of hydrogen gas

9 / 18

A chemist adds sodium hydroxide to ammonium nitrate solution. A gas is released that has a pungent smell. What does this confirm?

A) Bases decompose ammonium salts releasing ammonia.

B) Bases oxidize ammonium salts into acids.

C) Bases have no reaction with ammonium compounds.

D) Bases react with nitrates to form nitrogen gas.

10 / 18

Which statement correctly describes a key chemical property of bases?

A) They change all salts into gases.

B) They decompose into acids on heating.

C) They neutralize acids forming salt and water.

D) They always release hydrogen gas with metals.

11 / 18

When excess sodium hydroxide is added to ammonium chloride solution and heated, a gas is released. What role does sodium hydroxide play?

A) Oxidizing agent

B) Salt-forming catalyst only

C) Acid donor

D) Base releasing ammonia from ammonium salt

12 / 18

A student notices that mixing vinegar (acid) with sodium hydroxide produces a neutral solution. What does this indicate?

A) Bases convert acids into gases.

B) Bases destroy acids completely.

C) Acids and bases cancel each other’s properties.

D) Acids become bases after reaction.

13 / 18

Which of the following best explains why ammonium salts should not be heated with strong bases in a closed container?

A) Formation of liquid acid

B) Conversion into metals

C) Formation of explosive hydrogen gas

D) Release of ammonia gas increasing pressure

14 / 18

A base reacts with hydrochloric acid in a titration experiment. Which combination correctly represents the products?

A) Acid + base → metal + gas

B) Acid + base → hydrogen + oxygen

C) Acid + base → precipitate only

D) Acid + base → salt + water

15 / 18

A student adds sodium hydroxide to ammonium chloride and observes a colorless gas with a pungent smell. Which property of bases does this demonstrate?

A) Bases decompose into gases on heating.

B) Bases react with metals to form hydrogen.

C) Bases neutralize only organic acids.

D) Bases react with ammonium salts releasing ammonia.

16 / 18

Which observation would NOT occur during a reaction between a base and an ammonium salt?

A) Release of oxygen gas

B) Formation of salt

C) Evolution of ammonia gas

D) Change in litmus color

17 / 18

Why is ammonia gas considered a product of the reaction between bases and ammonium salts?

A) Because salts evaporate during reaction.

B) Because acids convert into gases.

C) Because ammonium ions decompose in presence of OH⁻ ions.

D) Because bases oxidize nitrogen compounds.

18 / 18

A chemist neutralizes a strong acid using a base. After completion, the pH of the solution becomes 7. What does this confirm about bases?

A) They decompose acids into elements.

B) They only react with metals.

C) They neutralize acids completely to form neutral solution.

D) They always increase acidity.

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