JEE Main levelSingle correct optionDifficulty 2 of 3cb195
n-Pentane boils at 36∘C but its isomer neopentane boils at 9.5∘C. The reason is that
An-pentane forms hydrogen bonds
Bneopentane is more compact and spherical, giving a smaller contact surface and weaker London forces
Cneopentane is a polar molecule
Dneopentane has a lower molar mass
Answer: B
The two are isomers (same molar mass), neither forms hydrogen bonds, and both are non-polar. The branched neopentane has less surface area for contact between molecules, so the dispersion forces are weaker and it boils lower.