Brownian motion can be observed under a microscope when looking at tiny pollen grains suspended in calm water.
What is the primary cause of the continuous, random movement of these pollen grains?
The pollen grains are constantly bombarded by fast-moving water molecules.
Convection currents in the water carry the pollen grains in random directions.
The pollen grains have different densities and rise or sink at different rates.
The pollen grains collide with the glass slide holding the water droplet.
321 exam-style questions on CIE IGCSE Physics 2.1 Kinetic particle model of matter, covering 2.1.1 States of matter and changes of state, 2.1.2a Particle structure and motion in solids, liquids and gases, 2.1.2b Gas pressure and particle collisions, 2.1.2c Brownian motion, 2.1.3a The absolute scale of temperature, and 2.1.3b Pressure, volume and temperature of a gas. Each one has a worked solution and a mark scheme showing where the marks go.