Class 12 NEET Chemistry Organic Compounds Containing Nitrogen

Concept:Alkyl halides react with $\mathrm{AgCN}$ to give isocyanides (carbylamines), which have a foul smell.In contrast, $\mathrm{KCN}$ gives cyanides (nitriles) which do not have a foul smell.Chemical Equation / Formula:$\mathrm{C}_2\mathrm{H}_5\mathrm{Cl} + \mathrm{AgCN} \longrightarrow \mathrm{C}_2\mathrm{H}_5\mathrm{NC} + \mathrm{AgCl}$Here, $\mathrm{C}_2\mathrm{H}_5\mathrm{NC}$ (ethyl isocyanide) is the foul‑smelling product $Z$.Explanation:• The given reaction shows $\mathrm{C}_2\mathrm{H}_5\mathrm{Cl}$ reacting with $X$ to produce $Z$.• $\mathrm{AgCN}$ is a covalent reagent, so the cyanide group attaches through carbon in $\mathrm{KCN}$ but through nitrogen in $\mathrm{AgCN}$, forming an isocyanide.• Isocyanides ($\mathrm{RNC}$) are well‑known for their foul smell, while cyanides ($\mathrm{RCN}$) have a pleasant odour.• Hence $X$ must be $\mathrm{AgCN}$ and $Z$ must be $\mathrm{C}_2\mathrm{H}_5\mathrm{NC}$.• This matches the image showing the second reaction also giving the same foul‑smelling product $Z$.Shortcut:Remember: “$\mathrm{AgCN}$ gives isocyanide (foul smell); $\mathrm{KCN}$ gives cyanide (no foul smell).”Answer:Option A ($X = \mathrm{AgCN}$, $Z = \mathrm{C}_2\mathrm{H}_5\mathrm{NC}$)