Atomic numbers of `Cr` and `Fe` are respectively `24` and `26`. Which of the following is paramagnetic with the spin of the electron?

Options

A. `[Cr(CO)_(6)]`
B. `[Fe(CO)_(5)]`
C. `[Fe(CN)_(6)]^(4-)`
D. `[Cr(NH_(3))_(6)]^(3+)`

Answer

D

Explanation

Atoms, ions or molecules having unpaired electrons are paramagnetic. in `[Cr(NH_(3))_(6)]^(3+)`, Cr is present as Cr (III).
`Cr^(3+)=1s^(2),2s^(2)2p^(6),3s^(2)3p^(6)3d^(3)` In excited state

Number of unpaired electrons = 3, so it is paramagnetic while rest of the species are diamagnetic.