When an ionic compound is dissolved in water (polar solvent), it breaks up into its constituent ions. The given ionic compound will be dissolved in water if its hydration energy is more than lattice energy . IF hydration energy is less than lattice energy then ionic compound is usually either sparingly soluble or insoluble in water.
Most hydrated cation is :

Options

A. `Ce_((aq.))^(4+)`
B. `La_((aq.))^(3+)`
C. `Ba_((aq.))^(2+)`
D. `Cs_((aq))^(+)`

Answer

A