Question

When both $N$ and $S$ are present in an organic compound, the sodium extract with $FeC{l}_3$ gives:

• A. Green colour
• B. Blue colour
• C. Yellow colour
• D. Blood red colour

Answer 1

The correct option is D Blood red colour

If both nitrogen and sulphur are present in an organic compound, Sodium thiocyanate is formed in the sodium extract.
$Na+C+N+S⟶NaSCN$

When the sodium extract containing $SC{N}^{-}$ ion is treated with $FeC{l}_3$ solution, it gives blood red colouration by formation of $\left[Fe\right(SCN){]}^{2+}$

$F{e}^{3+}+SC{N}^{-}⟶\underset{\text{Blood red colour}}{\left[Fe\right(SCN){]}^{2+}}$