Question

Which of the following are endothermic reactions?

I. Dilution of an acid

II. Reaction between water and quick lime

III. Sublimation of camphor

IV. Evaporation of a liquid

• A. I and II
• B. II and III
• C. I and IV
• D. III and IV

Answer 1

The correct option is D

III and IV

Explanation for the correct answer

During the dilution of acid, heat is released into the surroundings so, it is an exothermic reaction.

The reaction between water and quick lime produces heat along with the formation of Calcium hydroxide $\left(\mathrm{Ca}{\left(\mathrm{OH}\right)}_2\right)$.

During the sublimation of camphor and evaporation of a liquid, heat is absorbed from the surroundings so, it is an endothermic reaction.

Explanation for incorrect answer

Depending on the heat flow, the reaction is of two types.

Exothermic reaction: The reaction where heat is released to the surroundings is an exothermic reaction.

Endothermic reaction: The reaction where heat is absorbed from the surroundings is an endothermic reaction.

Hence option (a) is correct: dilution of acid and reaction between water and quick lime is an exothermic reaction.