Multiple choice

Permanent hardness of water can be removed by _____________.

  1. sodium sulphate

  2. sodium bicarbonate

  3. washing soda

  4. sodium chloride

  5. none of these

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

This option is correct because washing soda removes the permanent hardness by converting soluble calcium and magnesium compound into insoluble carbonates.