Millwright Level 1 Practice Exam

What happens to propane when it expands into gas?

1. It disperses quickly

2. It condenses

3. It creates a vacuum

4. It remains unchanged

The correct answer is: It disperses quickly

When propane expands into gas, it disperses quickly. This behavior is characteristic of gases, which tend to occupy the available volume and move rapidly to fill any space they are in. The process of expansion is influenced by the increase in temperature and decrease in pressure, which allows propane molecules to spread out and become less dense. This rapid dispersion is an essential property that has various practical applications, such as in propane heating systems where it needs to mix with air for efficient combustion. The dispersive nature of gases leads to their ability to flow and fill a container without remaining concentrated in one area. In contrast, the other options refer to different phenomena that do not occur during the expansion of propane from a liquid to a gas. For example, condensation refers to the process where a vapor turns back into a liquid, creating a vacuum involves an area of low pressure which is not directly related to propane expansion, and remaining unchanged contradicts the very nature of expansion which signifies a change in state from liquid to gas.