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

Answer

Elecrtronic configuration of `Mn^(2+ is 3d^(5)` which is half filled and hence stable . Therefore , `3rd` ionization enthalpy.is very high,i.e., 3rd electron cannot be lost easily. In case of `Fe^(2+)` , electronic configuration is `3d^(6)` . Hence , it can lose one electron easily to give the stable configuration `3d^(5)`