Question

The large difference between the melting and boiling points of oxygen and sulphur may be explained on the basis of

• A. Atomic size
• B. Atomicity
• C. Electronegativity
• D. Electron gain enthalpy

Hint:

The atomicity of sulfur \( (S_8) \) results in stronger intermolecular forces compared to oxygen \( (O_2) \), leading to a higher melting and boiling point for sulfur.

Answer 1

The Correct Option is B

Oxygen and sulfur belong to the same group in the periodic table, but their melting and boiling points differ significantly. The primary reason for this difference is atomicity, i.e., the number of atoms in a molecule of an element.
- Atomic size: While the atomic size of sulfur is larger than oxygen, this factor does not explain the large difference in melting and boiling points.
- Atomicity: Oxygen exists as \( O_2 \), a diatomic molecule, while sulfur exists as \( S_8 \), an eight-atom molecule. The larger atomicity of sulfur results in stronger intermolecular forces, higher boiling and melting points compared to oxygen.
- Electronegativity: Oxygen is more electronegative than sulfur, but this does not significantly affect the large difference in the melting and boiling points.
- Electron gain enthalpy: While oxygen has a higher electron gain enthalpy than sulfur, this factor doesn't explain the difference in their melting and boiling points.
Thus, the correct answer is (2) Atomicity, as the molecular structure of sulfur with \( S_8 \) leads to stronger intermolecular forces, which results in a higher melting and boiling point compared to oxygen.