Question

Which one of the following has the minimum boiling point?

• A. $n-butane$
• B. $1-butyne$
• C. $1-butene$
• D. Isobutene

Answer 1

The correct option is D Isobutene

Among the isomeric alkanes,the normal isomer has a higher boiling point than the branched chain isomer.The greater the branching of the chain,the lower is the boiling point.

The n-alkanes have larger surface area in comparison to branched chain isomer (as the shape approaches that of a sphere in the branched chain isomers).Thus,intermolecular forces are weaker in branched chain isomers.Therefore,they have lower boiling points in comparison to straight chain isomers.

Isobutane has minimum force of attraction due to sterric hindrance hence it has minimum boiling point.

Hence,D is correct option.