Question

The method used to remove temporary hardness of water is : 

(1) Calgon's method 

(2) Clark's method 

(3) Ion-exchange method 

(4) Synthetic resins method

Answer 1

Temporary hardness present in the water can be removed by using the following methods: 

By heating: Salts like calcium bicarbonate and magnesium bicarbonate, when dissolved in water causes temporary hardness. While heating, soluble salts of calcium and magnesium (bicarbonates) change into insoluble salts. 

Calcium bicarbonate → Calcium carbonate + Carbon dioxide + Water 

Treating with lime water: The temporary hardness of water can be removed by treating it with lime water. 

Calcium Bicarbonate + Calcium Hydroxide → Calcium Carbonate + Water.

Answer 2

The correct option is (2) Clark's method.

Explanation:

Clarks method is used to remove temporary hardness of water.