Question

Which of the following has intramolecular hydrogen bonding?

• A. Ethyl alcohol
• B. Ammonia
• C. O-nitrophenol
• D. Hydrofluoric acid

Hint:

Intramolecular hydrogen bonding often lowers boiling point compared to intermolecular hydrogen bonding because it reduces molecular association.

Answer 1

The Correct Option is C

Step 1: Understand intramolecular hydrogen bonding.
Intramolecular hydrogen bonding occurs when hydrogen bonding takes place within the same molecule, usually when suitable donor and acceptor atoms are positioned close to each other.
Step 2: Analyze each option.
(A) Ethyl alcohol: It shows intermolecular hydrogen bonding between different molecules, not within the same molecule.
(B) Ammonia: Hydrogen bonding occurs between different ammonia molecules, so it is intermolecular.
(C) O-nitrophenol: The hydroxyl hydrogen forms a hydrogen bond with the oxygen of the nitro group within the same molecule, resulting in intramolecular hydrogen bonding.
(D) Hydrofluoric acid: It exhibits strong intermolecular hydrogen bonding.
Step 3: Conclusion.
O-nitrophenol shows intramolecular hydrogen bonding due to favorable positioning of donor and acceptor groups.