Question

6. A divalent salt X, which contributes to hardness of water, combines with washing soda and insoluble salt Y and common salt. Salt Y is also used for the laboratory preparation of CO_2. Identify X and Y, respectively.

• A. CaSO₄ , CaCO₃
• B. MgSO₄ , MgCO₃
• C. CaCl₂ , CaCO3
• D. MgCl_{2 ,} MgCO₃

Answer 1

The correct option is C

CaCl₂ , CaCO3

Explanation of correct option:

(C) CaCl₂ , CaCO₃

Divalent metal salt X which contributes to hardness of water is CaCl₂ which combines with Na₂CO₃ (washing soda). It gives salt Y i.e. calcium carbonate and sodium chloride.

$$\begin{gathered} {\mathrm{CaCl}}_2+{\mathrm{Na}}_2{\mathrm{CO}}_3\to {\mathrm{CaCO}}_3+2\mathrm{NaCl} \\ \mathrm{Calcium}\mathrm{chloride}\mathrm{sodium}\mathrm{carbonate}\mathrm{Calcium}\mathrm{carbonte}\mathrm{sodium}\mathrm{chlodide} \end{gathered}$$

Hence (C) will be the correct option.