Question

The correct order of hydrogen bond strength and boiling point respectively is

• A. $HF>H_{2}O,H_{2}O>HF$
• B. $HF>H_{2}O,HF>H_{2}O$
• C. $H_{2}O>HF,H_{2}O>HF$
• D. $HF>H_{2}O,HF=H_{2}O$

Answer 1

The correct option is A $HF>H_{2}O,H_{2}O>HF$

Hydrogen bonding is the attractive interaction between hydrogen atom and a highly electronegative atom (O, F, N). As fluorine is more electronegative than oxygen, the hydrogen bonding in $HF$ is more stronger than that in $H_{2}O$.
But in $H_{2}O$, each water molecule is bonded to four other water molecules through intermolecular hydrogen bonding whereas in $HF$ molecule, one molecule can form only two hydrogen bonds. Thus, eventhough bond strength is high in $HF$, boiling point of water is higher than that of $HF$.