Multiple choice

Permanent harness of water is due to the presence of

  1. calcium bicarbonate

  2. magnesium bicarbonate

  3. calcium sulphate

  4. sodium bicarbonate

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Permanent hardness of water is caused by the presence of dissolved chlorides and sulphates of calcium and magnesium. Calcium sulphate is a primary contributor to this condition, which cannot be removed by simple boiling. In contrast, bicarbonates cause temporary hardness.