Question

Among the sulphates of alkaline earth metals, the solubility of ${\mathrm{BeSO}}_4$and ${\mathrm{MgSO}}_4$ in water, respectively, are

• A. Poor and high
• B. High and high
• C. Poor and poor
• D. High and poor

Answer 1

The correct option is B

High and high

Explanation for correct answer:

(B) High and high

1. The solubility of $2$nd group elements depends on their hydration energy which decreases down the group.
2. So, the solubility also decreases down the group.
3. $\mathrm{Be}$ and $\mathrm{Mg}$ are $2$nd and $3$rd group elements hence the solubility of their sulphates is high.

Explanation for incorrect options:

(A) High and poor

As $\mathrm{Be}$ and $\mathrm{Mg}$ are $2$nd and $3$rd group elements of group $2$ so the solubility of their sulphates cannot be high and poor.

(C) Poor and poor

As $\mathrm{Be}$ and $\mathrm{Mg}$ are $2$nd and $3$rd group elements of group $2$ so the solubility of their sulphates cannot be poor because solubility decrease down the group.

(D) Poor and high

As $\mathrm{Be}$ and $\mathrm{Mg}$ are $2$nd and $3$rd group elements of group $2$ so the solubility of their sulphates cannot be poor and high because solubility decrease down the group.

Hence, option B is correct, as the solubility of ${\mathrm{BeSO}}_4$and ${\mathrm{MgSO}}_4$ in water is high.