Identify the most basic compound from the following
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Ethyl amine
A compound is basic when it has a lone pair of electrons that can accept a proton. For amines, the more available the lone pair on nitrogen, the stronger the base:
Aliphatic amines: alkyl groups push electrons towards nitrogen (+I effect), so the lone pair is more available. Ethylamine (pKb 3.29) is a stronger base than ammonia (pKb 4.75).
Aromatic amines: the lone pair on nitrogen is delocalised into the benzene ring by resonance and is less available. Aniline (pKb 9.38) is a weaker base than ammonia.
Alcohols and aldehydes: they have no nitrogen. The lone pairs on the more electronegative oxygen are held tightly, so they are practically neutral in water.
So the order of basic strength is ethylamine > aniline > ethanol, ethanal, and the most basic compound is ethyl amine.
Why the other options are incorrect
Option (1) Aniline — Incorrect. It is a base, but a weak one, because resonance with the ring pulls the lone pair away from nitrogen.
Option (2) Ethanal — Incorrect. It is an aldehyde with no basic nitrogen; its oxygen lone pairs are only very weakly basic.
Option (3) Ethanol — Incorrect. It is neutral in water; it acts as a base only towards strong acids.
NCERT (2026-27 edition):
Basic Character of Amines – …
