The following two reactions give the same foul-smelling product $Z$. Reaction 1: $\ce{C2H5Cl + }X \ce{-> }Z$ Reaction 2: $\ce{C2H5CONH2 ->[Br2,\ NaOH]}$ $Y$ $\ce{->[\text{CHCl3 / ethanolic KOH}][\Delta]}$ $Z$ $X$ and $Z$, respectively, are :

Solution & Explanation

$\ce{AgCN}$ is a covalent, ambident nucleophile that bonds through nitrogen, so $\ce{C2H5Cl + AgCN -> C2H5NC + AgCl}$ gives ethyl isocyanide ($X = \ce{AgCN}$, $Z = \ce{C2H5NC}$). In Reaction 2, $\ce{C2H5CONH2}$ undergoes Hofmann degradation to ethylamine $\ce{C2H5NH2}$ ($Y$), which on the carbylamine reaction ($\ce{CHCl3}$ + ethanolic KOH) also gives the foul-smelling isocyanide $\ce{C2H5NC}$ ($Z$). Both routes converge on the same isocyanide.