Which of the following is an exothermic reaction?

A. dissolving sugar in water

B. oxidation of iron

C. dissolving ammunition nitrate in water to cool the water

D. melting ice

Answer: Option A) dissolving sugar in water

Explanation:

Sugar belongs to the class of food nutrients called carbohydrates, and it contains high energy bonds in its atoms that reacts with water thereby spontaneously releasing energy (in form of heat) to the surroundings.

Unlike others, energy is released when sugar is dissolved in water, thus the reaction is an example of exothermic reaction.