Physics 9702 · AS & A Level · Atoms, nuclei and radiation

Atoms, nuclei and radiation — practice question

Brownian motion may be shown by shining light on smoke particles in a sealed, transparent container. When the particles are examined with a microscope, bright points of light are seen to move in a continuous random manner. Which conclusion cannot be drawn from this observation?

  • AAir molecules are in constant motion.
  • BAir molecules are in random motion.
  • CAir pressure is due to air molecules colliding with the container.
  • DThe mass of an air molecule is much less than the mass of a smoke particle.

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