Question

Which of the following will cause softening of hard water?

• A. Passing it through sand.
• B. Passing it through cation exchange resin.
• C. Passing it through alumina
• D. None of the above

Answer 1

The correct option is B Passing it through cation exchange resin.

Passing it through cation exchange resin will cause the softening of hard water.
In cation exchange resin $M{g}^{2+}$ and $C{a}^{2+}$ (cations) are replaced by $N{a}^{+}$ ions.