alleryStart learning →The more compact shape of isopentane weakens its dispersion forces because it offers:
AA smaller contact surface
BA larger contact surface
CA stronger permanent dipole
DA greater molar mass
Answer & Solution
Correct answer: A. A smaller contact surface
1. Isomers of C5H12 share a molar mass, so mass cannot explain the difference.
2. Dispersion strength depends on how much of two molecules can touch.
3. The more compact shape of isopentane offers a smaller surface area available for intermolecular contact.
4. Therefore its dispersion forces are weaker than those of the straight-chain isomer.
_Source: OpenStax Chemistry 2e (CC BY 4.0), Ch 10 'Liquids and Solids', sections 10.1-10.6_
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