Sodium nitroprusside, $Na X_{2} [Fe (CN) X_{5} NO]$ , is used in the test for sulphide. Taking NO as $NO X^{+}$ , which statements are correct?

ASodium sulphite solution gives the same purple colour with nitroprusside in alkaline medium
B $[Fe (CN) X_{5} NO] X^{2 -}$ is diamagnetic
CIron is in the $+ 2$ oxidation state in $[Fe (CN) X_{5} NO] X^{2 -}$
DAlkaline sulphide solution gives a purple colour due to $[Fe (CN) X_{5} NOS] X^{4 -}$

Answer: B, C, D

With

NO X^{+}

(+1) and five

CN X^{-}

, charge balance

x + 1 - 5 = - 2

gives

x = + 2

. Fe(II) is

d^{6}

and low-spin with strong-field ligands, so all electrons are paired and the ion is diamagnetic. Sulphide attacks NO to give purple

[Fe (CN) X_{5} NOS] X^{4 -}

; sulphite does not give this purple colour with nitroprusside alone.