Question

Temporary hardness can be removed by which of the following process?

• A. By boiling
• B. By cooling
• C. By addition of lime
• D. By the addition of washing soda.

Answer 1

Answer: (A), (C), (D)

The correct options are
A

By boiling

C

By addition of lime

D

By the addition of washing soda.

Boiling - Compounds of calcium and magnesium are present in hard water and on boiling calcium and magnesium ions are removed from water by formation of insoluble calcium carbonate and magnesium carbonate and the water becomes soft.

On addition of lime and washing soda- calcium carbonates and other impurities settle down and can be removed by filtration.