Which oxide of a group 2 element is least soluble in water?
Solubility of group 2 oxides decreases down the group as lattice energy dominates over hydration energy. BaO (largest cation) is the least soluble among BeO, MgO, CaO, and BaO.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Genesis of Periodic Classification - Dobereiner Newlands Mendeleev