JEE Main · 2004 · 24 Apr 2004 · Offline · Chemical Bonding and Molecular Structure

Which one of the following has the minimum boiling point?

(A)n-butane
(B)isobutane✓ Correct
(C)1-butene
(D)1-butyne

Answer: (B)

Solution

Boiling point follows the strength of van der Waals attraction, which weakens when a molecule is more compact and branched and so exposes less surface. Of the

C X_{4}

species on offer, isobutane is the branched alkane and clings least to its neighbours, giving it the lowest boiling point, below the straight-chain n-butane and the unsaturated 1-butene and 1-butyne.

JEE Main · 2004 · 24 Apr 2004 · Offline · Single correct option

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