The upward displacement of air is a method used to collect gases that are denser than air, such as carbon dioxide (\(\rm CO_{2}\)).

 In this technique, the gas is allowed to flow into a container from below, pushing the lighter air upward and out of the container. Since the collected gas is denser, it stays at the bottom and displaces the air above it. This method is commonly used in laboratories for gases that won’t easily escape because of their higher density compared to air.