Question

$H_{2}O$ has a higher boiling point than HF. Which among the following is the right reason ?

• A. $H_{2}O$ is more polar than HF
• B. $H_{2}O$ can form more hydrogen bonds
• C. $H_{2}O$ has a higher molecular weight
• D. $H_{2}O$ has more atoms
• E. $H_{2}O$ does not have a higher boiling point than HF

Answer 1

The correct option is B $H_{2}O$ can form more hydrogen bonds

The correct answer is the option (B).
HF has higher polarity than water as fluorine is more electronegative than oxygen.
In HF molecule, only one H atom can form H bonds whereas in water molecule, two H atoms can form hydrogen bonds. Hence, the number of hydrogen bonds formed by one water molecule is twice the number of hydrogen bonds formed by one HF molecule. Higher is the number of hydrogen bonds, higher is the boiling point.