Question

Assertion (A): Permanent hardness of water is removed by treatment with washing soda.
Reason(R): Washing soda reacts with soluble magnesium and calcium sulphate to form water-soluble compounds.

• A. Statements (A) and (R) both are correct and (R) is the correct explanation of (A).
• B. (A) and (R) both are correct but (R) is not the correct explanation of (A).
• C. (A) is correct but (R) is not correct.
• D. (A) is not correct but (R) is correct.

Answer 1

The correct option is C

(A) is correct but (R) is not correct.

Permanent hardness is due to the presence of chlorides and sulphates of calcium and magnesium. This could be treated by adding $N{a}_{2}C{O}_3$, extracted from washing soda, which is soluble in water. It forms insoluble compounds with these compounds. Hence, the assertion is correct but the reason is incorrect.