Question

Which of the following molecules have intermolecular hydrogen bonds ?

• A. $Na{H}_{2}P{O}_2$
• B. $HF$
• C. $H_{3}B{O}_3$
• D. $(C{H}_3{)}_{3}B{O}_3$

Answer 1

Answer: (B), (C)

The correct options are
B $HF$
C $H_{3}B{O}_3$

$H-$ atom in $Na{H}_{2}P{O}_2$ is bonded with $P$ (less electronegative), cannot involve in $H-$ bonding and so also $(C{H}_3{)}_{3}B{O}_3$, $H-$ atom is bonded with $C$ (less electronegative atom). Hence, cannot involve in hydrogen bonding whereas in $H_{3}B{O}_3$, $H-$ atom is bonded with highly electronegative element i.e., oxygen. Hence, it shows intermolecular hydrogen bonding.
Intermolecular $H-$ bonding in $H_{3}B{O}_3$ is given as:
Flourine is the most electronegative element of the periodic table and hydrogen atom is bonded with flourine in $HF$. So, it will show intermolecular hydrogen bonding. Intermolecular $H-$ Bonding in $HF$