Brownian motion can be observed when pollen grains suspended in water are viewed under a microscope.
What causes the pollen grains to move in a random, jerky manner?
The pollen grains are carried by convection currents in the water.
The pollen grains are struck by constantly moving, invisible water molecules.
The pollen grains have different sizes and sink at different speeds.
The pollen grains repel each other due to static electrical charges.
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.