Brownian motion can be observed when using a microscope to look at pollen grains suspended in water.
What causes the pollen grains to move in a random, jerky manner?
Pollen grains are hit by fast-moving, invisible water molecules.
Pollen grains are moved by convection currents within the water.
Pollen grains have different shapes and swim actively through the water.
Pollen grains are repelled by electrostatic forces from the glass slide.
151 exam-style questions on CIE IGCSE Physics 2.1.2a Particle structure and motion in solids, liquids and gases. Each one has a worked solution and a mark scheme showing where the marks go.