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 insoluble 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) and (R) both are false

Answer 1

The correct option is A Statements (A) and (R) both are correct and (R) is the correct explanation of (A).

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