Question

Arrange the compounds in the order of decreasing boiling points.
1. Ethanol
2. Propane
3. Pentanol

• A. $1>2>3$
• B. $3>1>2$
• C. $1>3>2$
• D. $3>2>1$

Answer 1

The correct option is B $3>1>2$

The decreasing order of boiling points is Pentanol >Ethanol >Propane
($3>1>2)$

Pentanol and ethanol have H-bonding, but molecular mass of pentanol is more than ethanol, so it has high boiling point. Propane has the least boiling point due to non-polar character and weak van der waals forces of attraction.