Among ferrous and ferric ions, which one is more stable? Why? 

Explanation

Electroini configuration of Fe(26) `: [Ar] 4s^2 3d^6` Ferrous ion `Fe^(2+) : [Ar] 4s^0 3d^6` Ferric ion `Fe^(2+) : [Ar]4s^0 3d^6` Ferric ion is more stable than ferrous ion. This is because ferric ion has half filled d-subshell stable electronic configuration .