Difference in number of unpaired electron in `[Ni(H_2O)]_6Cl_2` and `[Ni(CN)_6]^(2-)`

The number of unpaired electron in Ni^(2+) is

The number of unpaired electrons in Ni (CO)_(4) is

The number of unpaired electron(s) in [Fe(H_2O)_6]^(2+) is

Find the number of unpaired electron in [Co(NH_3)_6]Cl_2 and [Co(NH_3)_6]Cl_3

Number of unpaired electrons present in [Ni(H_(2)O)_(6)]^(2+)

Number of unpaired electrons present in [Ni(H_(2)O)_(6)]^(3+)

Arrange the following in order of decreasing number of unpaired electrons. : I:[Fe(H_(2)O)_(6)]^(2+) " " II:[Fe(CN)_(6)]^(3-)" " III:[Fe(CN)_(6)]^(4-) " " IV:[Fe(H_(2)O)_(6)]^(3+)