Brownian motion can be observed when looking at pollen grains suspended in water under a microscope. What causes the pollen grains to move in this random, jerky manner?
The pollen grains are hit by rapidly moving, invisible water molecules.
The pollen grains are carried by convection currents in the water.
The pollen grains actively swim through the water.
The pollen grains occasionally collide with the walls of the container.
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.