Explain why `Cr^(2+)` is strongly reducing while `Mn^(3+)` is strongly oxidizing.

Explanation

`Cr^(+3)` is reducing in nature as its configuration changes from `d^(4)` to `d^(3)` (a stable configuration having half filled `t_(2g)` orbitals). On the other hand, `Mn^(+3)` is an oxidising agent in nature as its configuration changes from `d^(4)` to `d^(6)` (a stable configuration having half filled `t_(2g)` and `e_(g)` orbitals). Alternatively `E^(@)` value for `Cr^(+3)//Cr^(+2)` is negative (-0.41 V) where as `E^(@)` value for `Mn^(+3)//Mn^(+2)` is positive `(+1.51V)`. Hence `Cr^(+2)` ion can easily undergo oxidation to give `Cr^(+3)` ion and therefore, acts as a strong reducing agent. Whereas `Mn^(+3)` can undergo reduction to `Mn^(+2)` ion and hence action as a oxidising agent.