Question

Why nicl4 2 is paramagnetic and ni co 4 is diamagnetic?

Answer 1

[NiCl4]2 is paramagnetic and [Ni(CO) 4] is diamagnetic because

1. The paramagnetism of any material depends upon the unpaired electron
2. The oxidation state of Ni in [NiCl4] is +2
3. The oxidation state of Ni in [Ni(CO)4] is 0
4. So there is no unpaired electron in the [Ni(CO)4] it shows diamagnetic behaviour
5. While [NiCl4]2 has unpaired electron it shows paramagnetic  behaviour.