MCQ
The decreasing order of boiling points is
  • $n-$ Pentane > iso-Pentane > neo-Pentane
  • B
    iso-Pentane > $ n-$ Pentane > neo-Pentane
  • C
    neo-Pentane > iso-Pentane >$ n-$ Pentane
  • D
    $n-$ Pentane > neo-Pentane > iso-Pentane

Answer

Correct option: A.
$n-$ Pentane > iso-Pentane > neo-Pentane
a
As the boiling point of an alkane depends on the surface area of a molecule, higher the surface is, higher the boiling point of alkane. The branched-chain isomer of an alkane has a lower surface area than that of its straight-chain isomer, so the branched-chain isomer of an alkane has a lower boiling point than its straight-chain isomer.

So, higher the branches, lower is the boiling point.

So, the order of boiling point of isomeric pentanes is $n -$ pentane $\,>\,$ iso $-$ pentane $\,>\,$ neo $-$ pentane.

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