Question

give reason that for dilution of acid , acid is added to water and not water into acid

Answer 1

The process of dissolving an acid or a base in water is a highly exothermic one. Care must be taken while mixing concentrated nitric acid or sulphuric acid with water. The acid must always be added slowly to water with constant stirring. If water is added to a concentrated acid, the heat generated may cause the mixture to splash out and cause burns. The glass container may also break due to excessive local heating. 

Answer 2

Explanation:

for dilution of acid acid is added into water not water into acid because if we add water into acid it forms an extremely concentrated solution of acid initially. So much heat is released that the solution may boil very violently splashing concentrated acid out of the container and all this because solution is exothermic.