Physics · Oct / Nov 2020 · Paper 11 · Question 25

A smoke particle Z is seen to move randomly when suspended in air as illustrated. [diagram of random path of particle Z] Which statement explains why Z moves randomly?

1. AAir molecules are much larger than Z.
2. BAir molecules are smaller than Z.
3. CAir molecules hit Z from different directions.
4. DAir molecules vibrate about a fixed position.

As printed in the paper