Chemistry - Halogen Derivative Question with Solution | TestHub

If both nitrogen and sulphur are present in a organic compound, they will give red blood colour with Lassaigne test due to the formation of ferric thiocyanate. $\begin{array}{rl}& \mathrm{Na}+\mathrm{C}+\mathrm{S}+\mathrm{N}\stackrel{\Delta }{\to }\mathrm{NaSCN}\\ & \text{ sodium. thiocyanate }\\ & {\mathrm{Fe}}^{3+}+3\mathrm{NaSCN}⟶\mathrm{Fe}(\mathrm{SCN}{)}_3+3{\mathrm{Na}}^{+}\\ & \text{ferric thiocyanate }\\ & \text{ (blood red colouration) }\\ & \end{array}$