Question

Hard water is not available for an experiment. Some salts are given below :

(I) Sodium chloride

(II) Sodium sulphate

(III) Calcium chloride

(IV) Calcium sulphate

(V) Potassium chloride

(VI) Magnesium sulphate

Select from the following group of these salts, each member of which may be dissolved in water to make it hard.

(A) I, II, V

(B) I, III, V

(C) III, IV, VI

(D) II, IV, VI

Answer 1

Hard water contains sulphates, chlorides and bicarbonates of calcium and magnesium. To make water hard, calcium chloride, calcium sulphate and magnesium sulphate should be added to it.

Hence, the correct option is C.