Certified Transport Registered Nurse Certification Practice Exam

As altitude increases, how do gas molecules behave?

1. They become larger and move faster

2. They become fewer and take up less space

3. They become denser and move more slowly

4. They become sparse and take up more space

The correct answer is: They become sparse and take up more space

As altitude increases, gas molecules become sparse and take up more space. This change is primarily due to the decrease in atmospheric pressure at higher altitudes. At lower altitudes, air is denser because there is more atmospheric pressure pushing down on the gas molecules, causing them to be closer together. As you ascend, the pressure decreases, which allows gas molecules to spread out more. This results in a lower density of gas molecules and an increased volume occupied by the remaining gas in a given area. Consequently, the behavior of gas molecules at higher altitudes reflects reduced density and increased spacing, illustrating how the physical principles of gas behavior and atmospheric conditions interact.