When pollen grains suspended in water are observed under a microscope, they exhibit Brownian motion. Which of the following best describes the motion of these pollen grains?
Moving in a single uniform direction.
Vibrating about fixed positions.
Moving in a continuous, random, zigzag path.
Remaining completely stationary.
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.