Which of the following metal ions has a calculated magnetic moment value of `sqrt(24)` BM ?

Options

A. `Mn^(2+)`
B. `Fe^(2+)`
C. `Fe^(3+)`
D. `Co^(2+)`

Answer

B

Explanation

`mu_(eff)=sqrt(24)BM`
`mu_(eff)=sqrt(n(n+2))`
n=no. of unpaired electrons
`mu_(eff)=sqrt(4(4+2))=sqrt(24)BM`
`=2.sqrt(2).sqrt(3)`
`=2xx1.414xx1.732=4.89BM`
In the given option only `Fe^(+2)` has 4 unpaired electrons .