Q58 / 200 · NEET 2022 (Phase 2) · Chemistry

The decreasing order of boiling points of the following alkanes is: (a) Heptane (b) butane (c) 2-methylbutane (d) 2-methylpropane (e) hexane Choose the correct answer from the options given below:

  • A
    (a) $>$ (c) $>$ (e) $>$ (d) $>$ (b)
  • B
    (c) $>$ (d) $>$ (a) $>$ (e) $>$ (b)
  • C
    (a) $>$ (e) $>$ (b) $>$ (c) $>$ (d)
  • Correct answer
    D
    (a) $>$ (e) $>$ (c) $>$ (b) $>$ (d)

Solution

With increase in molecular mass, van Der Waal force increases and hence boiling point also increases. $\therefore$ BP : Heptane \(>\) Hexane \(>\) 2- Methyl Butane \(>\) Butane \(>\) 2- methly propane with the increase in branching, surface area decreases of molecules of same molecular mass which results in decrease in boiling point.

Hence, the correct answer is option: 'D'.

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