How Does basic character of the oxides down the group in alkali metals change . Give reason

The alkali metal oxides are basic in nature. They can easily donate hydroxide ion to the solution. As we move down the group, the size of the metal ion increases, so the bonding between the metal and hydroxide ion is weak. Hence, they can easily lose $O{H}^{-}$ ion. So, down the group, the basicity of alkali metal oxides and hydroxides increases.

$BasiccharacterofOxides:L{i}_{2}O<N{a}_{2}O<K_{2}O<R{b}_{2}O<C{s}_{2}O$