Calculate the magnetic moments of `Fe^(2+)` and `Fe^(3+)`

Explanation

`Fe^(2+)`, there are 4 unpaired electrons
`mu= sqrt(4(4 + 2)) = sqrt(4xx6) =sqrt24 = 4.89 B.M`
In `Fe^(3+)` there are 5 unpaired electrons. `mu = sqrt(5(5+2)) = sqrt(5xx7)=sqrt135 =5.91 B.M`