Consider the following complex ions, P, Q, and R. P=FeF63−,Q=VH2O62+ and R=FeH2O62+, the correct order of the complex ions, according to their spin only magnetic moment values (in B. M.) is:

FeF63−P→Fe3+→d5 configuration, F- is weak field ligand Unpaired electrons = 5; ∴ μ=55+2=5.95 B.M.VH2O62+Q→V+2→d3 configuration, H2O is weak field ligand Unpaired electron = 3; ∴ μ=33+2=3.87 B.M.FeH2O62+R→Fe+2→d6 configuration, H2O is weak field ligand Unpaired electron = 4; ∴ μ=44+2=4.90 B.M.Therefore only spin magnetic moment μ=nn+2B.M. (n = unpaired electron) So, μ of P > R > Q.