`[Fe(H_(2)O)_(5)NO]^(2+)` is a complex formed during the brown ring test for `NO_(3)^(-)` ion. In this complex.

Options

A. NO transfers its electron to `Fe^(2+)` so that we have iron as `Fe(I)` and NO as `NO_^(+)`
B. There are three unpaired electron so that its magnetic moment is 3.87 B.M.
C. The colour is due to charge transfer
D. All the above statements are correct.

Explanation

`HgI_(2)overset(Delta)(rarr) Hg_ I_(2) ("violet vapours")`
`NO rarr NO^(+) + e^(-)`,
`{:(Fe^(2+) ,+,e^(-),rarr,Fe^(+)),((3d^(6)),,,,(3d^(7))),("4 unpaired "e^(-),,,,"3 unpaired "e^(-)):}`
`mu` for `Fe^(+) = sqrt(n(n+2))= sqrt(3 xx 5)` BM
`= sqrt(15) BM =3.87 BM`