State and explain the trend in the solubility of the s block sulphate down the group

For Group 1 sulfates (e.g., $\text{Li}_2\text{SO}_4$, $\text{Na}_2\text{SO}_4$), solubility increases down the group.
For Group 2 sulfates (e.g., $\text{BeSO}_4$, $\text{MgSO}_4$, $\text{CaSO}_4$, $\text{SrSO}_4$, $\text{BaSO}_4$), solubility decreases down the group.

The solubility of an ionic compound depends on the balance between its lattice energy (energy required to break the ionic lattice) and its hydration energy (energy released when ions are hydrated by water molecules).

For Group 1 sulfates, the sulfate ion ($\text{SO}_4^{2-}$) is large. As you go down the group, the size of the cation ($\text{Li}^{+}$ to $\text{Cs}^{+}$) increases. The decrease in lattice energy (due to increasing cation size) is more significant than the decrease in hydration energy, leading to an increase in solubility.

For Group 2 sulfates, the sulfate ion ($\text{SO}_4^{2-}$) is large. As you go down the group, the size of the cation ($\text{Be}^{2+}$ to $\text{Ba}^{2+}$) increases. The decrease in hydration energy (due to increasing cation size and thus decreasing charge density) is more significant than the decrease in lattice energy. This means less energy is released upon hydration, making the compounds less soluble. Therefore, the solubility of Group 2 sulfates decreases down the group.