During diffusion, what causes particles to spread out over time?

During diffusion, what causes particles to spread out over time?

• A. Random motion of particles.
• B. External forces only.
• C. Gravity only.
• D. Magnetic fields only.

Answer: (A)

Diffusion is driven by the random motion of particles due to their thermal energy. Each particle moves unpredictably and collides with others, so particles naturally spread from regions of higher concentration to regions of lower concentration. Over time, this random movement leads to a more uniform distribution without needing an outside push. External forces, gravity, or magnetic fields can influence movement in some situations, but diffusion itself comes from the inherent random motion of the particles.

Diffusion is driven by the random motion of particles due to their thermal energy. Each particle moves unpredictably and collides with others, so particles naturally spread from regions of higher concentration to regions of lower concentration. Over time, this random movement leads to a more uniform distribution without needing an outside push. External forces, gravity, or magnetic fields can influence movement in some situations, but diffusion itself comes from the inherent random motion of the particles.