The reducing power of a metal depends on various factors. Suggest the factor which makes Li, the strongest reducing agent in aqueous solution.

Alkali metals are strong reducing agents, with lithium being the strongest and sodium being the weakest reducing agent. Li is has the smallest atomic size and the highest hydration enthalpy. Hydration enthalpy is the amount of energy released when one mole of ions undergo hydration. Due to this, Li is the strongest reducing agent.