JAMB - Chemistry (2001 - No. 41)
The gas that can best be collected by downward displacement of air is
Chlorine
Sulphur (IV) oxide
Ammonia
Carbon (IV) oxide
Explicación
The method used to collect a gas depends on whether it is denser or lighter than air. For example, ammonia gas is collected by downward displacement of air because it is lighter than air. Option C is the correct answer.
Chlorine is heavier than air.
SO\(_2\) is denser than air.
CO\(_2\) is denser than air.