The amines which are soluble in water
(A) Methanamine
(B) Ethanamine
(C) Propanamine
(D) Benzylamine
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → (A), (B) and (C) only
Amines dissolve in water because the –\( \ce{NH2} \) group forms hydrogen bonds with water molecules. The hydrocarbon part of the molecule cannot form such bonds, so solubility decreases as the hydrophobic part grows; the lower aliphatic amines are soluble, while the higher amines are essentially insoluble.
(A) Methanamine, \( \ce{CH3NH2} \) — Correct. One carbon atom; it is very soluble in water.
(B) Ethanamine, \( \ce{C2H5NH2} \) — Correct. Two carbon atoms; it is soluble in water.
(C) Propanamine, \( \ce{CH3CH2CH2NH2} \) — Correct. Three carbon atoms; it is still a lower aliphatic amine and soluble in water.
(D) Benzylamine, \( \ce{C6H5CH2NH2} \) — Not included in the answer given by NTA. Its hydrophobic part, the \( \ce{C6H5CH2-} \) group of seven carbon atoms, is much larger than in the three lower aliphatic amines, and solubility decreases as the hydrophobic part grows.
NCERT (2026-27 edition):
Physical Properties – …
