Which one of the following shows highest magnetic moment?

Options

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

Answer

A

Explanation

`""_(26)Fe^(2+): 3d^(6) 4s^(0)` contains 4 unpaired electrons
`""_(27)Co^(2+), 3d^(7) 4s^(0)` contains 3 unpaired electrons.
`""_(28)Ni^(2+), 3d^(8) 4s^(0)` contains 3 unpaired electrons.
`""_(28)Ni^(2+), 3d^(8) 4s^(0)` contains 2 unpaired electrons.
Hence, `Fe^(2+) (n=4)` has highest magnetic moment.