Chemistry - PRACTICAL ORGANIC CHEMISTRY Question with Solution | TestHub

$\underset{\mathrm{Lassaigne}\text{'}\mathrm{s} \mathrm{extract}}{{\mathrm{Na}}_2\mathrm{S}}+{\mathrm{Na}}_2\left[\mathrm{Fe}(\mathrm{CN}{)}_5\mathrm{NO}\right]\to \underset{\mathrm{Purple} \mathrm{colour}}{{\mathrm{Na}}_4\left[\mathrm{Fe}(\mathrm{CN}{)}_5\mathrm{NOS}\right]}$

On treating sodium fusion extract with sodium nitroprusside, appearance of a violet colour further indicates the presence of sulphur.