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.
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.