Question

Which of the following has least boiling point?

• A. 3-Pentanol
• B. n-Pentane
• C. 2, 2,-Dimethyl Propanol
• D. n- Pentanol

Answer 1

The correct option is B

n-Pentane

The decreasing order of boiling points is:

n-Pentanol $>$ 2, 2-Dimethyl propanol

Alcohols (4), (3), and (1) have H-bonding, but n-pentanol is a straight-chain compound and has a larger surface area, (so the highest boiling point). Alcohol (3) is more sterically hindered than alcohol (1), hence it requires more energy to boil off. Therefore, boiling point of alcohol (3) $>$ alcohol (1).