Lassaigne's test gives a violet colour with sodium nitroprusside. It indicates the presence of\

Question

Professor PC Thomas Classes · Answer

57. $\mathrm{Na}_{2} \mathrm{~S}+\mathrm{Na}_{2}\left[\mathrm{Fe}(\mathrm{CN})_{5} \mathrm{NO}ight] ightarrow$
$$
\mathrm{Na}_{4}\left[\mathrm{Fe}(\mathrm{CN})_{5} \mathrm{NOS}ight]
$$
$$
	ext { or } \mathrm{S}^{2-}+\left[\mathrm{Fe}(\mathrm{CN})_{5} \mathrm{NO}ight]^{2-} ightarrow
$$
[Fe(CN) ${ }_{5}$ NOS] ${ }^{4-}$ ( violet)