Question

Assertion $\left(A\right):$ Permanent hardness of water is removed by treatment with washing soda.

Reason $\left(R\right):$ Washing soda reacts with soluble magnesium and calcium sulphate to form insoluble carbonates.

• A. Both A and $R$ 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

Both A and $R$ are correct and $R$ is the correct explanation of $A.$

Washing soda $\left(N{a}_{2}C{O}_3\right)$ reacts with soluble calcium and magnesium chlorides and sulphates in hard water to form insoluble carbonates and thus removes hardness of water.

$MC{l}_2+N{a}_{2}C{O}_3\to MC{O}_3\downarrow +2NaCl$

$(M=Mg,Ca)$

$MS{O}_4+N{a}_{2}C{O}_3\to MC{O}_3\downarrow +N{a}_{2}S{O}_4$

So, option $\left(A\right)$ is correct. Hence, statements $A$ and $R$ both are correct and $R$ is the correct explanation of $A.$