Question

The d-electron configurations of `Cr^(2+), Mn^(2+), Fe^(2+)` and `Co^(2+)` are `d^4, d^5, d^6` and `d^7` respectively. Which one of the following will exhibit minimum paramagnetic behavious?
A. (a) `[Cr(H_2O)_6]^(2+)`
B. (b) `[Mn(H_2O)_6]^(2+)`
C. (c) `[Fe(H_2O)_6]^(2+)`
D. (d) `[Co(H_2O)_6]^(2+)`

Answer 1

Correct Answer - D
`H_2O` is weak field ligand, thus `CO^(2+)` has only 3 unpaired electrons.