How would a gas behave in a closed container?

In a closed container, a gas behaves in such a way that it takes the shape of the container. This occurs because gas particles are in constant, rapid motion and have a significant amount of space between them, resulting in the ability to move freely and spread out to fill the entire volume available. Unlike solids and liquids, gases do not have a definitive shape; instead, they conform to the shape of their surroundings.

This characteristic distinguishes gases from other states of matter. For example, while a solid maintains a fixed shape and volume, and a liquid has a fixed volume but takes the shape of its container, gases fully occupy any container they are placed in, regardless of the container's shape. This property can be observed in everyday situations, such as when you inflate a balloon; the air inside the balloon presses against the walls and takes on the shape of the balloon.

Choices emphasizing fixed volume or distinct shape do not apply to gases in this scenario, as they fundamentally lack these characteristics. Furthermore, the assertion that a gas cannot change under pressure is misleading; gases can be compressed and will usually change volume significantly in response to increasing pressure. This highlights the unique and versatile behavior of gases within closed environments.