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Solubility of the alkaline earth metal sulphates in water decreases in the sequence:
A
Mg > Ca > Sr > Ba
B
Ca > Sr > Ba > Mg
C
Sr > Ca > Mg > Ba
D
Ba > Mg > Sr > Ca
Detailed Solution
Solubility depends on the balance between lattice enthalpy and hydration enthalpy.
Down the group both decrease, but hydration enthalpy falls more sharply (the large $SO_4^{2-}$ ion keeps lattice enthalpy nearly constant).
So the solubility of group 2 sulphates decreases down the group: Mg > Ca > Sr > Ba.
Down the group both decrease, but hydration enthalpy falls more sharply (the large $SO_4^{2-}$ ion keeps lattice enthalpy nearly constant).
So the solubility of group 2 sulphates decreases down the group: Mg > Ca > Sr > Ba.