JEE Main · 2023 · 25 Jan 2023 · Shift 2 · Compounds Containing Nitrogen

Basic strength runs opposite to $\mathrm{p}{K}_b$, so the stronger base has the smaller $\mathrm{p}{K}_b$. In aniline the nitrogen lone pair is delocalised into the ring, making it the weakest base and fixing its $\mathrm{p}{K}_b$ at $9.38$. Among the aliphatic amines the secondary diethylamine is the strongest base in water and takes $\mathrm{p}{K}_b=3.00$, the tertiary triethylamine comes next at $3.25$, and primary ethanamine at $3.29$. Matching each amine with its value gives aniline with $9.38$, ethanamine with $3.29$, N-ethylethanamine with $3.00$ and N,N-diethylethanamine with $3.25$.