Question

Which of the following is not true?

• A. The hardness of water depends on its behaviour towards soap.
• B. The temporary hardness is due to the presence of calcium and magnesium bicarbonates.
• C. Permanent hardness is due to the presence of soluble calcium and magnesium sulphates, chlorides and nitrates.
• D. Permanent hardness can be removed by boiling the water.

Answer 1

The correct option is D

Permanent hardness can be removed by boiling the water.

The hardness of water depends on its behaviour towards soap. Hard water is water that does not give lather with soap.

The presence of calcium and magnesium salts in the form of hydrogencarbonate, chloride and sulphate in water makes water hard.

The temporary hardness in water is due to the presence of magnesium and calcium hydrogen carbonates. It can be removed by boiling.

Permanent hardness in water is due to the presence of soluble salts of calcium and magnesium, chlorides and sulphates.

Permanent hardness of water cannot be removed by boiling it.