Which of the following best describes molecular motion according to the kinetic molecular theory?

• A. Molecules are in constant, random motion and collide elastically with each other and the walls of the container.
• B. Molecules move in fixed paths and only interact with the walls of the container.
• C. Molecules remain stationary unless energy is added to the system.
• D. Molecules move in a single direction until they lose energy and stop.

Answer: (A)

Verified step by step guidance

1. Recall the main postulates of the kinetic molecular theory, which describes the behavior of gas particles (molecules).
2. Understand that according to the theory, molecules are always in motion, and this motion is random and constant, not fixed or stationary.
3. Recognize that molecules collide with each other and with the walls of their container, and these collisions are elastic, meaning no kinetic energy is lost during collisions.
4. Eliminate options that suggest molecules move in fixed paths, remain stationary, or move in a single direction until stopping, as these contradict the theory's description of random, continuous motion.
5. Conclude that the best description is that molecules are in constant, random motion and collide elastically with each other and the container walls.