Question

Solid calcium oxide reacts vigorously with water to form calcium hydroxide accompanied by liberation of heat. This process is called slaking of lime. Calcium hydroxide dissolves in water to form its solution called lime water. Which among the following is (are) true about slaking of lime and the solution formed?
(i) It is an endothermic reaction.
(ii) It is an exothermic reaction.
(iii) The pH of the resulting solution will be more than seven.
(iv) The pH of the resulting solution will be less than seven.
(A) (i) and (ii) (B) (ii) and (iii)
(C) (i) and (iv) (D) (iii) and (iv)

Answer 1

(B) (ii) and (iii)

Slaking of lime is accompanied by liberation of heat, hence it is an exothermic reaction. Calcium hydroxide is an alkali and its aqueous solution (i.e., lime water) turns red litmus blue. Thus, the pH of the solution will be more than seven.