Question

$HCl$ gas cannot be dried by passing through:

• A. $H_{2}S{O}_4$
• B. $CaO$
• C. $P_2{O}_5$
• D. $CO$

Answer 1

Answer: (B), (C)

The correct options are
B $CaO$
C $P_2{O}_5$

$CaO$ and $P_2{O}_5$ are basic in nature so when $HCl$ is based over them, they will react with $HCl$ and form Salt and water, whereas $H_{2}S{O}_4$ and $CO$ are an acidic and hence greater affinity for water. So they can be used to dry $HCl$.