Brownian motion can be observed under a microscope when looking at pollen grains suspended in water.
What causes the pollen grains to move in a random, jerky motion?
Convection currents in the water carry the pollen grains.
Pollen grains are hit by water molecules moving randomly at high speeds.
Pollen grains have different masses and sink at different speeds.
Pollen grains collide with the glass slide.
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.