Question

Which of the following has the maximum vapour pressure?

• A. $HCl$
• B. $HBr$
• C. $HF$
• D. $HI$

Answer 1

Answer: (A)

$HCl$ is the most volatile compound among all hydrogen halides. The volatility of a compound is related to its high vapour pressure at ordinary temperature. $HF$ due to hydrogen bonding is least volatile, as the molecular weight increases, intermolecular forces increases due to van der Waals' force of attraction. Thus, $HI$ is liquid and $HCl$ is gas with maximum vapour pressure among all hydrogen halides