Question

The alkaline earth metal sulphate(s) which are readily soluble in water is/are:
(a) BeSO₄
(b) MgSO₄
(c) CaSO₄
(d) SrSO₄
(e) BaSO₄
Choose the correct answer from the options given below:

• A. Only a and b
• B. Only a, b, c
• C. Only d and e
• D. Only a and e

Hint:

To remember solubility trends, note that alkaline earth metal sulphates become less soluble as you move down the group. This is due to the decreasing hydration energy of the cations.

Answer 1

The Correct Option is A

Step 1: Understand the Solubility Trends of Alkaline Earth Metal Sulphates
The solubility of alkaline earth metal sulphates decreases down the group due to the decrease in hydration energy. Hydration energy is the energy released when ions interact with water molecules. Higher hydration energy leads to better solubility.
Step 2: Analyze BeSO\(_4\) and MgSO\(_4\)
-BeSO\(_4\): Due to its small size and high charge density, the Be\(^{2+}\) ion exhibits very high hydration energy. This makes BeSO\(_4\) highly soluble in water.
-MgSO\(_4\): The Mg\(^{2+}\) ion also has high hydration energy, leading to good solubility of MgSO\(_4\) in water.
Step 3: Analyze the Remaining Sulphates
CaSO\(_4\), SrSO\(_4\), and BaSO\(_4\): As we move down the group, the size of the cations increases, reducing the charge density and hydration energy. This results in lower solubility. Hence, these sulphates are sparingly soluble or insoluble in water.
Conclusion:
From the analysis, BeSO\(_4\) and MgSO\(_4\) are the only sulphates that are readily soluble in water. Therefore, the correct answer is \((3)\) A and B.