Question

$HCl$ is a gas but HF is a low boiling liquid. This is because

• A. $HF$ bond is strong
• B. $HF$ bond is weak
• C. molecules aggregate because of hydrogen bonding
• D. HF is a weak acid

Answer 1

Answer: (C)

HF is a low boiling liquid due to the presence of hydrogen bonding in the molecules. Due to hydrogen bonding in HF molecules it exist as associated molecules ${(HF)}_n$ . $---H-F--HF---HF---HF---$ or ${(HF)}_n$ $HCl$ is a gas due to absence of hydrogen bonding in the molecules. Hydrogen bond is formed between H-atom and most electronegative atom (like, N, O and F).