Permanent hardness of water is due to
- AChlorides and sulphates of Calcium and Magnesium
- BCalcium bicarbonate sulphates
- CMagnesium bicarbonate
- DChlorides of Silver and Potassium
Show answer and explanation
Correct answer: (a) Chlorides and sulphates of Calcium and Magnesium
Explanation
Permanent hardness comes from the chlorides and sulphates of calcium and magnesium (CaCl₂, MgCl₂, CaSO₄, MgSO₄). Boiling does not remove it; washing soda or ion exchange does.
Temporary hardness comes from the bicarbonates of calcium and magnesium, and boiling removes it.