\(x+4(0)=0 \)
\(x=0\)
The electronic configuration of \(Ni\) is \([ Ar ] 3 d ^{8} 4 s ^{2} 4 p ^{0} .\) The orbital diagram of nickel in the presence of strong filed ligand \(CO\) is shown below.
As no unpaired electron is present in this complex, so it is diamagnetic.
$(i)$ $[Ni(CO)_4], \,sp^3$
$(ii)$ $[Ni(CN)_4]^{2-}, \,sp^3$
$(iii)$ $[CoF_6]^{3-}, \,d^2sp^3$
$(iv)$ $[Fe(CN)_6]^{3-}, \,sp^3d^2$