[" Why is Cr2+ strongly reducing "],[" and Mn3+ strongly oxidising "],[" when both have d4"]

Why Cr^(2+) is strongly reducing while Mn^(3+) is strongly oxidising ?

Account for the following statements : (i) Co (ii) is stable in aqueous solution but in the presence of strong ligands and air it can get oxidised to Co (III) (at. No Co=27) (ii) of the d^4 species Cr (II) is strongly reducing but Mn (III) is strongly oxidising (at. no Cr= 24 , Mn = 25, Co = 27)

Account for the following: (i) Transition elements exhibit higher enthalpies of atomisation. (ii) Cr^(2+) is reducing and Mn^(3+) is oxidising when both have d^4 configuration.

Why is Cr^(2+) reducing and Mn^(3+) oxidising when both have d^4 configuration?

Why is Cr^(2+) reducing and Mn^(3+) oxidising when both have d^(4) configuration ?

Why is Cr^(2+) reducing and Mn^(3+) oxidising when both have d^(4) configuration ?