Consider the following complex ions P, Q and R: `P=[FeF_6]^(3-), Q=[V(H_2O_6)]^(2+) ,R=[Fe(H_2O)_6]^(2+)` The correct order of the complex ionis, according to their spin-only magnetic moment values (in BM)is

Options

A. `R lt Q lt P`
B. `Q lt R lt P `
C. `R lt P lt Q`
D. `Q lt P lt R`

Answer

B

Explanation

`P= Fe^(3+) (3d^5)` (number of unpaired electrons =5)
`Q = V^(2+)(3d^3)`(number ofurpaired electrons= 3)
`R=Fe^(2+)(3d^6)` (number of unpaired electróns = 4)

As all ligands are weak field, hence the number of unpaired electrons remains samne in the complex ion.
`therefore mu_(MM) "of " P gt R gt Q`
Hence B is correct.