Consider the follwing complexes ion `P,Q` and `R`
`P =[FeF_(6)]^(3-), Q=[V(H_(2)O)_(6)]^(2+)` and `R=[Fe(H_(2)O)_(6)]^(2+)`
The correct order of the complex ions, according to their spin only magnetic moment values (inBM) is .

Options

A. `RltQltP`
B. `QltRltP`
C. `RltPltQ`
D. `QltPltR`.

Answer

B

Explanation

(b) P=`FeF_(6)]^(3-)`
`Fe^(3+)(3d^(5) =`
No. of unpaired electrons =5
Magnetic momentum (m) `=sqrt(n(n+2))BM=sqrt(5(5+2))BM=sqrt(35)=5.92 BM `
`Q=[V(H_(2)O)_(6)]^(2+)`
`V^(2+)(3d^(3) =`
No. of unpaired electrons =3
Magnetic moment (m) `=sqrt(3(3+2))BM=sqrt(15)=3.87 BM`
`R=[Fe(H_(2)O)_(6)]^(2+)`
`Fe^(2+)(3d^(6))=`
No. of unpaired electrons =4
Magnetic moment (m) `=sqrt(4(4+2)) BM=sqrt(24)=4.09 BM`
The correct order of spin-only magnetic moment values is `Q lt R lt P`