Question

Assertion :$BaS{O}_4$ is insoluble in water. Reason: Lattice energy of $BaS{O}_4$ is higher than its hydration energy.

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
• C. Assertion is correct but Reason is incorrect
• D. Both Assertion and Reason are incorrect

Answer 1

The correct option is A Both Assertion and Reason are correct and Reason is the correct explanation for Assertion

In the alkaline earth metals, the lattice energy of sulphates remains constant but the hydration energy decreases from $B{e}^{2+}$ to $B{a}^{2+}$ appreciably as the size of cation increases down the group.
Hence, due to decrease in hydration energy, the solubility of sulphates decreases down the group.
And as Mg is very smaller than Ba in size so $MgS{O}_4$ is soluble but at the bottom of the group the solubility of $BaS{O}_4$ becomes least and it becomes insoluble in water.