MCQ
The decreasing order of boiling points is
- ✓$n-$ Pentane > iso-Pentane > neo-Pentane
- Biso-Pentane > $ n-$ Pentane > neo-Pentane
- Cneo-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.
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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