Question

Which of the following are exothermic reactions?

L Dilution of an acid III. Sublimation of camphor III. Reaction between water and quick lime IV. Evaporation of a liquid

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

Answer 1

The correct option is B

I and III

Exothermic reactions

These are the chemical reactions in which heat is liberated.

The products formed during this reaction are less energetic than the reactants.

Explanation

i. During the dilution of an acid, a large amount of heat is released. So, it is an exothermic process.

ii. For a sublimation reaction, heat is absorbed. So, it is an endothermic physical change.

iii. The reaction between water and quick lime forms Calcium hydroxide $\left(\mathrm{Ca}{\left(\mathrm{OH}\right)}_2\right)$ along with the evolution of heat. So, it is an exothermic process.

iv. For the evaporation of water, heat is absorbed. So, it is an endothermic physical change.

Hence option (b) is correct., dilution of acid and the reaction between water and quick lime are exothermic changes.