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

• A. The random movement of particles suspended in a fluid due to collisions with molecules of the fluid.
• B. The uniform, straight-line motion of gas molecules in a vacuum.
• C. The process by which gases condense into liquids at low temperatures.
• D. The orderly arrangement of particles in a crystalline solid.

Answer: (A)

Verified step by step guidance

1. Understand that Brownian motion refers to the movement of small particles suspended in a fluid (liquid or gas).
2. Recall from the kinetic molecular theory that particles in fluids are in constant, random motion and collide with suspended particles.
3. Recognize that these collisions cause the suspended particles to move in a random, jittery manner, which is what Brownian motion describes.
4. Eliminate options that describe uniform motion, phase changes, or solid-state arrangements, as these do not match the concept of Brownian motion.
5. Conclude that the best description is the random movement of particles suspended in a fluid due to collisions with molecules of the fluid.