Question

Which of the following alkane has the least boiling point?

• A. n-butane
• B. n-pentane
• C. isopentane
• D. neopentane

Answer 1

The correct option is D neopentane

This is due to the fact that branching of the chain makes the molecule more compact and thereby decreases the surface area. Therefore, the intermolecular attractive forces which depend upon the surface area, also become small in magnitude on account of branching. Consequently, the boiling points of the branched-chain alkanes are less than the straight-chain isomers.