Predict the number of unpaired electrons in the square planar Pt[(CN)4]2- ion

 In Pt[(CN)4]2- ion:

Overall charge balance:

X + 4(-1) = -2

X = + 2.

The oxidation state of Pt is + 2.

Since CN- is a strong field ligand ,it causes pairing of the unpaired electrons.

Therefore now the 2 unpaired electrons from 5d orbital get paired and it undergoes dsp2 hybridisation. It forms square planar geometry. Since all the electrons are paired ,

No. of unpaired electrons = 0.