Question

Identify the examples of diffusion in the list below. Check all that apply.

A teacher takes the cap off a permanent marker. A few minutes later, students at the back of the classroom complain about the odor of the marker.

A cooking school student burns a piece of toast. Soon, the entire kitchen smells like burnt toast.

An inflated balloon shrinks when it is placed in a cold freezer.

Toxic fumes produced by a chemical factory are detected in the air in a town several miles away.

Heating a flexible container filled with gas causes it to expand.

Answer 1

Diffusion is the net movement of particles from regions of higher concentration to lower concentration (by random molecular motion). The examples that show diffusion are:

- A teacher takes the cap off a permanent marker (vapors spread through the classroom).
- A student burns toast (smell molecules spread through the kitchen).
- Toxic fumes from a factory detected miles away (fumes disperse through the air).

Not diffusion:
- Balloon shrinks in a freezer — this is thermal contraction of the gas (ideal‑gas behavior), not diffusion.
- Heating a flexible container causes expansion — this is thermal expansion/pressure change, not diffusion.