Why is water (H₂O) a liquid at room temperature with a boiling point of 100°C, whereas hydrogen sulfide (H₂S) is a gas boiling at -60°C despite its higher molar mass?

Answer and explanation

Correct answer: D. water molecules form extensive intermolecular hydrogen bonds due to oxygen's high electronegativity

  1. Step 1: Oxygen is much more electronegative than sulfur, creating strong O-H dipoles. Step 2. Water molecules participate in extensive intermolecular hydrogen bonding, requiring substantial thermal energy to separate. Step 3. In H₂S, sulfur is insufficiently electronegative to form hydrogen bonds; only weaker dipole-dipole forces exist. Answer: water molecules form extensive intermolecular hydrogen bonds due to oxygen's high electronegativity. Why not the others: Covalent bonds are intramolecular; dispersion forces alone do not outweigh hydrogen bonds; sulfur does not carry higher formal charge.

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