a. Water should not be added to concentrated acid because the process of dissolving an acid or a base in water is a highly exothermic one. If water is added to an acid then the heat generated may cause the acid to splash out and cause burns.

b. Pain or irritation is caused in our stomach when there is production of an excess amount of acid in our body. Antacids are basic in nature. Hence antacids are required when there is pain or irritation in the stomach to neutralize the effect of the excess acid.

c. Bee-stung injects acid in our body. Baking soda is a base. Hence, baking soda should be rubbed on bee-stung area to neutralize the effect of the acid.