A teacher uses a microscope to observe tiny smoke particles suspended in air.
Which statement describes the reason for the random movement of these smoke particles?
Air molecules are moved by microscopic smoke particles.
Air molecules are moved by smoke molecules.
Microscopic smoke particles are moved by air molecules.
Smoke molecules are moved by air molecules.
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.