Chemistry - s Block Elements Question with Solution | TestHub

As hydration energy$\propto$charge on cation$\propto \frac{1}{\text{size of cation}}$
As on moving down size of ion increases so degree of hydration decreases hence the correct order is
$\mathrm{L}{\mathrm{i}}_{\left(\mathrm{a}\mathrm{q}\right)}^{+}>\mathrm{N}{\mathrm{a}}_{\left(\mathrm{a}\mathrm{q}\right)}^{+}>{\mathrm{K}}_{\left(\mathrm{a}\mathrm{q}\right)}^{+}>\mathrm{R}{\mathrm{b}}_{\left(\mathrm{a}\mathrm{q}\right)}^{+}>\mathrm{C}{\mathrm{s}}_{\left(\mathrm{a}\mathrm{q}\right)}^{+}$