Q42 - States of matter

The correct answer is A) The intermolecular forces in A are stronger than those in B.

When a liquid boils, its molecules separate from each other, but the molecules themselves stay intact: steam is still H₂O. So boiling only overcomes the intermolecular forces (hydrogen bonds, dipole–dipole, London forces). The stronger they are, the higher the boiling point.

Example: H₂O (100 °C) and H₂S (about −60 °C) have similar shapes, but water forms hydrogen bonds.

A) Correct: Stronger intermolecular forces mean a higher boiling point.

B) Incorrect: Intramolecular forces (covalent bonds inside the molecule) are not broken during boiling.

C) Incorrect: Weaker forces would give a lower boiling point.

D) Incorrect: Same mistake as B: bonds inside the molecule do not decide the boiling point.

E) Incorrect: Weaker intermolecular forces in A would give A the lower boiling point.