Question

Why are `Mn^(2+)` compounds more stable than `Fe^(2+)` towards oxidation to their +3 state?

Answer 1

`Mn^(2+)` has electronic configuration `[Ar]4s^(0)3d^(5)`.
`Fe^(+2)` has electronic configuration `[Ar]4s^(0)3d^(6)`.
`rarr Mn^(+2)` has half filled d-subshell which is more stable.
`rarr` Hence `Mn^(+2)` compound are more stable than `Fe^(+2)` toward oxidation to their +3 state.