What is the electron configuration of Co2+ and how many unpaired electrons are in the free transition metal ion?
(a) [Ar]3d54s2; 5 unpaired electrons
(b) [Ar]3d54s2; 1 unpaired electron
(c) [Ar]3d7; 3 unpaired electrons
(d) [Ar]3d7; 1 unpaired electron