Brownian motion can be observed when tiny particles, such as pollen grains or smoke particles, are suspended in a fluid.
Which statement correctly explains the cause of this Brownian motion?
The suspended particles are carried by convection currents arising from temperature differences in the fluid.
The suspended particles collide with each other due to electrostatic repulsion.
The suspended particles are bombarded by the rapidly-moving, invisible molecules of the fluid.
The suspended particles continuously absorb light energy, which drives their random movement.
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.