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) Decomposition reaction

B) Neutralization reaction

C) Displacement reaction

D) Redox 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 decompose acids into elements.

B) Bases increase acidity of solutions.

C) Bases neutralize acids to form salt and water.

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 react with ammonium salts to release ammonia gas.

B) Bases form precipitates with all salts.

C) Bases neutralize salts into acids.

D) Bases produce oxygen gas with salts.

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 react with ammonium salts producing ammonia gas.

C) Bases convert salts into metals.

D) Bases decompose acids into hydrogen 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 form insoluble salts only.

B) Bases are corrosive in all conditions.

C) Bases react with ammonium salts to liberate ammonia.

D) Bases change into acids on heating.

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) Exothermic neutralization reaction

B) Formation of gas bubbles only

C) Physical mixing without reaction

D) Endothermic decomposition of acid

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) Oxygen

B) Carbon dioxide

C) Ammonia

D) Hydrogen

8 / 18

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

A) Production of hydrogen gas

B) Evolution of oxygen gas

C) Formation of salt and water

D) Formation of a colored precipitate

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 react with nitrates to form nitrogen gas.

B) Bases decompose ammonium salts releasing ammonia.

C) Bases have no reaction with ammonium compounds.

D) Bases oxidize ammonium salts into acids.

10 / 18

Which statement correctly describes a key chemical property of bases?

A) They decompose into acids on heating.

B) They neutralize acids forming salt and water.

C) They change all salts into gases.

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) Acid donor

B) Base releasing ammonia from ammonium salt

C) Oxidizing agent

D) Salt-forming catalyst only

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) Acids become bases after reaction.

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

D) Bases destroy acids completely.

13 / 18

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

A) Conversion into metals

B) Formation of explosive hydrogen gas

C) Formation of liquid acid

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 → salt + water

B) Acid + base → metal + gas

C) Acid + base → precipitate only

D) Acid + base → hydrogen + oxygen

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 react with ammonium salts releasing ammonia.

D) Bases neutralize only organic acids.

16 / 18

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

A) Evolution of ammonia gas

B) Change in litmus color

C) Formation of salt

D) Release of oxygen gas

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 bases oxidize nitrogen compounds.

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

D) Because acids convert into gases.

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 only react with metals.

B) They neutralize acids completely to form neutral solution.

C) They decompose acids into elements.

D) They always increase acidity.

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