Why is `+2` oxidation state of manganese quite stable while the same is not true for iron?`[Mn=25,Fe=26]`.

Explanation

The electronic configuration of both the ions are :
`Mn^(2+): [Ar]3d^(5),Fe^(2+):[Ar]3d^(6)`
The `Mn^(2+)` ion has more symmetrical configuration than `Fe^(2+)` ion and is therefore, more stable. Thus, +2 oxidation of manganese is quite stable while that of iron is not.