In alkali metal group which is the strongest reducing agent and why?

Q: In alkali metal group which is the strongest reducing agent and why?

Sol: Li is the strongest reducing agent. Since I.P. decreases down the group we would expect that Li will have the lowest reducing power in that group. But since it’s hydration energy is very high and which in fact decreases down the group, Li will have highest reducing power.

(ii)Although Aluminium is above hydrogen in the electrochemical series, it is stable in air and water. Explain.

Sol: (ii) Due to the formation of protective oxide layer on its surface.