When a strong acid, strong base or their salt are dissolved in water, they are completely ionised.

If a strong acid is added to a strong base, H+ ions from the former combine with oH- ions of the

latter forming water. The formation of each water molecule liberates certain quantity of energy and

the reaction is exothermic. The heat liberated when one mole of water is formed by combining

hydrochloric acid and sodium hydroxide is 13.7 kcal. The heat liberated when one mole of water is

formed by combining sulphuric acid and sodium hydroxide is

(1) 25.5kcal (2) 8.5kcal (3) 13.7kcal (4) 34kcal