Answer: the compound that dissolves in water by an exothermic process is NaOH. The correct option is 2.
Step-by-step explanation:
A chemical reaction is defined as the combination of two or more chemical substances which leads to the formation of new products. During a chemical reaction, heat is either absorbed or released into the environment.
A reaction is ENDOTHERMIC if it absorbs heat from the environment when it takes place. Reactions which releases heat to the surroundings on the other hand are called EXOTHERMIC reactions.
When NaOH which is a strong base dissolves in water, it dissociates into its various component ions Na+ and OH- ions with the release of heat into the environment. This makes it a typical example of an exothermic reaction.