Question

The decreasing order of boiling points is

• A. neo-pentane $>$ iso-pentane $>n$ -pentane
• B. iso-pentane $>n$ -pentane $>$ neo-pentane
• C. $n$ - pentane $ > $ iso-pentane $ > $ neo-pentane
• D. $n$ -pentane $>$ neo-pentane $>$ iso-pentane

Answer 1

Answer: (C)

For isomeric alkanes, with branching the surface area of the molecule decreases and hence van der Waals force of attraction is less. So, boiling point decreases with branching of alkanes. Therefore, the decreasing order of boiling point of pentanes is $n$ -pentane $>$ iso-pentane $>$ neo-pentane.