Chemistry 2001 JAMB Past Questions - Question 46: The gas that can best be collected by downward displacement of air is

Correct Answer

C

Explanation

The gas that can best be collected by downward displacement of air is ammonia (NH3). Ammonia is lighter than air, so when it is released, it tends to rise. Collecting it by downward displacement ensures that it is collected in the container without mixing with the surrounding air.

When collecting gases by downward displacement of air, the principle is to allow the gas being collected to displace the air in the container, causing the air to move upward and out of the container. This is effective for gases that are lighter than air.

It's worth noting that some gases are denser than air and can be collected by upward displacement. The choice of collection method depends on the specific properties of the gas being collected.