Question

Account for the following:

Mn²⁺ is more stable than Fe²⁺ towards oxidation to +3 state.

Answer 1

 Electronic configuration of Mn²⁺ is [Ar]¹⁸ 3d⁵ .
    Electronic configuration of Fe²⁺ is [Ar]¹⁸ 3d⁶ .
 It is known that half-filled and fully-filled orbitals are more stable. Therefore, Mn in +2 state has a stable d⁵configuration. Therefore, Mn²⁺  shows resistance to oxidation to Mn³⁺. Also, Fe²⁺ has 3d⁶ configuration and by losing one electron, its configuration changes to a more stable 3d⁵ configuration. Therefore, Fe²⁺ gets oxidised to Fe³⁺ easily.