The reducing power of a metal depends on various factors. Suggest the factor which makes Li, the strongest reducing agent in aqueous solution.
(i) Sublimation enthalpy
(ii) Ionisation enthalpy
(iii) Hydration enthalpy
(iv) Electron-gain enthalpy
With the small size of Li+ ion, lithium has the highest hydration enthalpy which accounts for its high negative Eo value and its high reducing power.