Same chapter3 marksDifficulty: Medium
Why is sulphur hexafluoride known but not sulphur hexachloride?
p-Block Elements
3 marksDifficulty: Medium
Why is the boiling point of hydrogen fluoride higher than that of hydrogen chloride?
Original Khojo Papers practice question — not from a past board paper.
Answer
Fluorine is small and highly electronegative, so hydrogen fluoride molecules are joined by strong hydrogen bonds that need considerable energy to break. Hydrogen chloride forms no significant hydrogen bonds and is held only by weaker dipole-dipole and dispersion forces, so it boils lower despite its greater molecular mass.
No citable source has been recorded for this record. Treat it as practice material, not as fact.
Explanation
The same anomaly appears for water and ammonia in their own groups.
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