Lesson T6.1.3

T6.1.3 Diffusion and Brownian motion Quiz: KS3 Physics, Unit 6

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson T6.1.3, Diffusion and Brownian motion: 20 multiple choice questions for the KS3 Physics (National Curriculum), Unit 6: Matter and particles, written with Revision Ninja.

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The 20 questions

  1. What is the net movement of particles from high to low concentration called?

    • Sublimation
    • Melting
    • Diffusion
    • Evaporation

  2. In which state of matter does diffusion happen the fastest?

    • Gas
    • Liquid
    • Plasma
    • Solid

  3. What drives the process of diffusion?

    • Concentration gradient
    • External pressure
    • Magnetic force
    • Gravity

  4. What process causes food colouring to spread evenly through still water?

    • Condensation
    • Diffusion
    • Evaporation
    • Sublimation

  5. Why is diffusion slower in liquids than in gases?

    • Frequent particle collisions
    • Particles lack energy
    • Temperature is zero
    • Particles are larger

  6. What term describes the random jiggling of tiny visible particles in a fluid?

    • Diffusion
    • Convection
    • Radiation
    • Brownian motion

  7. What causes the random motion of smoke particles under a microscope?

    • Thermal convection
    • Magnetic forces
    • Light wave pressure
    • Air molecule collisions

  8. What physical process causes a cooking smell to cross a room?

    • Condensation
    • Evaporation
    • Diffusion
    • Sublimation

  9. How does increasing temperature affect the rate of gas diffusion?

    • Stops it entirely
    • Makes it faster
    • Makes it slower
    • Has no effect

  10. What do visible particles in Brownian motion demonstrate about surrounding fluid particles?

    • Regular circular orbits
    • Uniform downward flow
    • Stationary fixed positions
    • Random constant motion

  11. Which process is shown when sugar slowly spreads through a cup of tea?

    • Freezing
    • Evaporation
    • Melting
    • Diffusion

  12. In what direction do perfume particles move during diffusion?

    • Towards heat sources
    • High to low concentration
    • Downward by gravity
    • Low to high concentration

  13. What process causes bromine gas to spread upwards into a jar of air?

    • Condensation
    • Evaporation
    • Sublimation
    • Diffusion

  14. What effect does a larger concentration difference have on diffusion?

    • No effect
    • Reversed diffusion
    • Faster diffusion
    • Slower diffusion

  15. Why do ink particles spread out in water over time?

    • Magnetic attraction
    • Convection currents
    • Random particle collisions
    • Chemical reactions

  16. Which phenomenon demonstrates Brownian motion using a microscope?

    • Water boiling
    • Ice melting
    • Pollen grains jiggling
    • Salt dissolving

  17. Why is diffusion extremely slow in solid materials?

    • Strong magnetic pull
    • High density barrier
    • Fixed particle positions
    • Large particle size

  18. What is true about the movement of particles causing diffusion?

    • Move in straight lines
    • Constantly moving randomly
    • Stop when mixed
    • Vibrate without moving

  19. Why does dye spread faster through hot water than cold water?

    • Water becomes less dense
    • Water particles move faster
    • Gravity increases
    • Dye particles shrink

  20. What can be observed when smoke particles jiggle in still air?

    • Gas particles moving
    • Gravity fading
    • Light bending
    • Air cooling down

All KS3 Physics quizzes