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.
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.