Give reason for the fact that amongst `Ni(CO)_(4)[Ni(CN)_(4)]^(2-)` and `NiCI_(4)^(2-), Ni(CO)_(4)` and `[Ni(CN)_(4)]^(2-)` are diamagnetic whereas `[NiCI_(4)]^(2)` is paramagnetic are diamagnetic whereas` [NiCI_(4)]^(2)` is paramagnetic .

Explanation

In`[Ni(CO)_(4)]` oxidation rate of Ni is zero

Since `CO` is strong field ligands pairing of electrons takes place and hence `n = 0 Ni (CO)_(4)` is diamagntic In `[Ni(CN)_(4)]^(2-)` ion Ni exist as `Ni^2+` ion

Since `CN^(Θ)` is strong field ligands it forces the two unpaired electrons are paired up `[Ni(CN)_(4)]^(2-)` is diamagnetic
In `[NiCI_(4)]^(2-)` Ni exist as `Ni^(2+)` ion
`"Since"^(Θ)` is weak field ligand no pairing up of electrons in `3d` orbitals takes place hence `n=2` and `[NiCi^(4)]^(2-)` is paramagntic .