Which among the following compounds has highest boiling point?

Which among the following compounds has highest boiling point?
  1. Propanal
  2. Ethanal
  3. Pentanal
  4. Hexanal

Solution

The boiling point of organic compounds within the same homologous series increases with molecular weight due to stronger London dispersion forces between larger molecules.

Among propanal (3 carbon atoms), ethanal (2 carbon atoms), pentanal (5 carbon atoms), and hexanal (6 carbon atoms), hexanal possesses the highest molecular weight.

Hexanal exhibits the strongest intermolecular forces and therefore the highest boiling point.

The correct answer is $D$.

Asked in: MHT CET 2025 (23 April Shift 1)

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