Question

per dilution of acid acid is added into water and not water into acid why

Answer 1

Dear student,
Addition of acid into water is a highly exothermic reaction and yields a lot of heat energy. Also, the specific heat capacity of water is very high. So when we add acid to water slowly drop by drop, the water shall absorb the heat released and prevent any accident. But if water is added to acid, this may cause a release of lot of heat energy and sometimes, when the acid is concentrated and very strong, an explosion may occur. Thus, on dilution of any acid, the acid is dropped slowly into the water.
Regards.