Tiny pollen grains suspended in water are observed under a microscope. They are seen to move in a continuous, random, and jittery path (Brownian motion).
What does this observation tell us about the water molecules?
The water molecules are much larger and heavier than the pollen grains.
The water molecules are in constant, rapid, and random motion.
The water molecules are attracted to each other by strong gravitational forces.
The water molecules are completely stationary and form a solid structure.
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.