Question

Least volatile hydrogen halide is

• A. HF
• B. HCl
• C. HI
• D. HBr

Answer 1

Answer: (A)

As the size of halogen atom increases, the boiling point of hydrogen halides increases. However, $HF$ has the highest boiling point among the hydrogen halides because of $H$-bonding and
Boiling point $\alpha \frac{1}{\text{ volatility }}$
Thus, $HF$ is least volatile among hydrogen halides.