Hard water contains dissolved salts such as magnesium and calcium chlorides, bicarbonates, or sulphates. There are two kinds of hardness of water, i.e. temporary hardness and permanent hardness.
Temporary hardness can be removed by

Options

A. boiling hard water.
B. adding slaked lime.
C. adding dil. `H_2 SO_4`
D. adding milk of magnesia.

Answer

A, B