Kaplan Nursing Entrance Practice Exam

Which of the following statements best describes the motion of gas particles?

1. They move in straight lines until they collide.

2. They move in fixed pathways.

3. They remain stationary until an external force acts on them.

4. They move only when heated.

The correct answer is: They move in straight lines until they collide.

The statement that gas particles move in straight lines until they collide accurately describes the behavior of gas molecules according to the kinetic molecular theory. This theory posits that gas particles are in constant random motion, and their movement is characterized by traveling in straight paths until they encounter other particles or walls of the container. During such collisions, the particles may change direction, but the straight-line motion is a fundamental aspect of their behavior in the absence of other influences. This straight-line motion also underscores the low density and high compressibility of gases compared to liquids and solids. The particles are far apart and have minimal interaction unless they collide, allowing them to move freely and rapidly. The other statements do not represent the nature of gas particles accurately. Fixed pathways would imply that they follow a specific route, which is not true in the context of gases. Stating that they remain stationary until acted upon implies a level of rigidity that does not apply to the free-moving characteristics of gases. Lastly, the notion that gas particles only move when heated does not capture the concept of gas motion, as they can move irrespective of temperature, although their kinetic energy and speed increase with heating.