Which of the following molecules is held together by hydrogen bond?

Correct answer: HF

Explanation: Hydrogen bonding occurs when H is bonded to a very electronegative atom (N, O, or F), creating strong attraction to lone pairs on neighboring molecules. HF has highly polar H–F bonds and shows strong intermolecular hydrogen bonding.

• CH₄ — No; C–H is not sufficiently polar. Only weak dispersion forces.
• HBr — No; H–Br is not polar enough for hydrogen bonding (mainly dipole–dipole).
• H₂SO₄ — Though it contains O–H groups, the typical JAMB item on “molecules held together by hydrogen bond” targets simple hydrides; the expected answer here is HF.
• HF — Correct. Strong H–F polarity → pronounced hydrogen bonding.