Spin only magnetic moment,
µ=√n(n+2)BM where,
n= number of unpaired electrons and
µ∝n.
(i)
[FeF6]3−⇒Fe3+=(3d5)+6×F−(weak field ligand).
Thus, pairing of electron does not take place.
(ii)
[Co(NH3)6]3+⇒Co3+=(3d6)+6×NH3 (strong field ligand).
Thus, pairing of electron takes place.
(iii)
[NiCl4]2−⇒Ni2+=(3d8)+4×Cl−(weak field ligand).
Thus, pairing of electron takes place.
(iv)
[Cu(NH3)4]2+⇒Cu2+(3d9)+4×NH3 (strong field ligand).
Thus, pairing of electron takes place.
So, the decreasing order of
µ is
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