When d orbitals are half-filled or completely filled, the oxidation state is more stable. Thus, Mn (Z=25) has an electronic configuration [Ar]3d54s2. +2 oxidation state is most stable as it has a stable electronic configuration (half-filled 3d orbital). Also, Zn (Z = 30) has an electronic configuration [Ar]3d104s2.. +2 oxidation state is most stable as it has a stable electronic configuration (completely filled 3d orbital).