The correct option is D (A)≈(C)≈(D)<(B)
(A)Ni(CO)4
Ni is in the zero oxidation state i.e., it has a configuration of 3d84s2. Since CO is a strong field ligand, it causes the pairing of unpaired 3d electrons. so number of unpaired electron is zero thus it is diamagnetic.
μ=0 B.M;diamagnetic.
(B) [Ni(H2O)6]Cl2
[Ni(H2O)6]2+
Ni2+=3d8 with weak field ligand.
∴Number of unpaired e−=2
μ=√n(n+2)
=√2(2+2)=2√2 B.M.
(C) Na2[Ni(CN)4]
[Ni(CN)4]2−
Ni2+=3d8 with strong field ligand CN−. so it will paired up d electron.
Number of unpaired e−=0
∴μ=0B.M
PdCl2(PPh3)2
Pd2+=4d8(diamagnetic)
μ=0B.M
(D)PdCl2(PPh3)2
Pd is in the +2 oxidation state i.e., it has a configuration of 4d85s0. Since (PPh3) is a strong field ligand, it causes the pairing of unpaired 3d electrons. so number of unpaired electron is zero thus it is diamagnetic.
μ=0 B.M;diamagnetic.
Hence, the correct order is A≈C≈D<B
Therefore, the correct option is D.