Lesson T3.2.1

T3.2.1 Filtration and evaporation Quiz: KS3 Chemistry, Unit 3

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson T3.2.1, Filtration and evaporation: 20 multiple choice questions for the KS3 Chemistry (National Curriculum), Unit 3: Pure and impure substances, written with Revision Ninja.

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The 20 questions

  1. What is filtration used to separate?

    • Two gases from a mixture of air
    • Two soluble solids dissolved in a liquid
    • An insoluble solid from a liquid
    • A pure element from a compound

  2. What does the filter paper do in filtration?

    • It heats the mixture so the solid melts and passes through the paper
    • It dissolves the solid so the solid passes through with the liquid
    • It lets the liquid pass through but traps the solid particles
    • It attracts the solid with a magnet so the solid is pulled out

  3. What is the liquid that passes through the filter paper called?

    • The filtrate
    • The catalyst
    • The residue
    • The solute

  4. What is the solid left behind on the filter paper called?

    • The solute
    • The solvent
    • The filtrate
    • The residue

  5. Why is sand mixed with water separated by filtration?

    • Sand is magnetic, so it is pulled out of the water by a magnet placed beside the beaker
    • Sand does not dissolve in water, so its grains are too large to pass through the filter
    • Sand dissolves in the water, so it is removed when the liquid is poured through the filter
    • Sand evaporates faster than the water, so it disappears from the beaker before the water does

  6. How is evaporation used to get salt from salt water?

    • The water is heated until it turns into vapour, leaving salt crystals behind
    • The salt is filtered out through the paper as the mixture is poured through the funnel
    • The water is cooled until the salt melts and then drains off the crystals
    • The salt is pulled out with a magnet placed in the solution for a few minutes

  7. Why does evaporation leave a solid behind from a solution?

    • The solute evaporates first and leaves behind the solvent as a liquid
    • The solvent turns into vapour and the solute is left as solid
    • The solute and solvent both turn into a gas that escapes from the dish
    • The solute reacts with the solvent to make a gas that escapes into the air

  8. A student evaporates a salt solution until the water has gone. Which result is expected?

    • A gas is collected in a balloon
    • Salt crystals remain in the dish
    • A metal ring forms around the dish
    • A layer of sand forms in the dish

  9. A student wants to separate chalk from water. Which method is most suitable?

    • Filtration, because chalk is insoluble
    • Chromatography, because chalk is a dye
    • Distillation, because chalk turns to gas
    • Evaporation, because chalk dissolves

  10. What is important when setting up a filter funnel so the filtrate comes out clear?

    • The funnel is heated until the solid melts and then drips into the beaker
    • The filter paper is properly seated and the mixture is poured carefully
    • The mixture is poured in quickly so that the solid settles before the filter
    • The filter paper is removed so that the solid can dissolve in the liquid below

  11. Why is evaporation slow when a salt solution is left in a cold room?

    • Particles at the surface become heavier in the cold, so they sink back into the liquid
    • Particles at the surface turn into a solid layer that covers the whole liquid
    • Particles at the surface have less energy at low temperature, so fewer escape as vapour
    • Particles stop moving when the room is cold, so they cannot leave the liquid at all

  12. Which method separates the soil from muddy water?

    • Chromatography
    • Melting
    • Distillation
    • Filtration

  13. Which method separates salt from salt water, leaving the salt as a solid?

    • Filtration
    • Magnetic separation
    • Sieving
    • Evaporation

  14. Why should filter paper be placed fully in the funnel?

    • So no liquid passes around the edge without being filtered
    • So the filter paper can absorb the solid into its fibres
    • So the filter paper can heat the liquid
    • So the filter paper can dissolve the residue

  15. Which statement about filtration is correct?

    • Filtration separates two soluble solids from each other
    • Filtration separates an insoluble solid from a liquid
    • Filtration separates two gases by density
    • Filtration separates a compound into its elements

  16. Why is filtration done before evaporation when separating a mixture of sand, salt and water?

    • To make the salt melt in the hot mixture so that it can be evaporated off more quickly
    • To remove the insoluble sand so that only the salt solution remains for evaporation
    • To remove the water first so that the sand can be dried in the open air before the salt
    • To turn the salt into a gas so that it can be collected in the condenser tube

  17. What does it mean if the filtrate is still cloudy?

    • The liquid has turned into a gas during the filtering process itself
    • The filter paper has dissolved into the liquid and dissolved the solid
    • The solid has become a pure element that is too small to be filtered
    • Some fine solid particles have passed through the filter paper

  18. Why is evaporation to dryness better than pouring the water away when recovering salt?

    • It removes the salt from the water by burning it
    • It converts the salt into a liquid for storage
    • It removes all the oxygen from the water
    • It keeps the salt, which is the solute, in solid form

  19. Which order correctly separates a mixture of sand, salt and water?

    • Use a magnet to remove salt, then evaporate the sand
    • Filter to remove sand, then evaporate the water to leave salt
    • Heat to make the sand melt, then filter the salt
    • Evaporate to remove sand, then filter to collect salt

  20. Why does a residue need to be dried after filtration before weighing?

    • Water remaining in the residue would add extra mass and give a false result
    • Water in the residue would change the residue into a gas that escapes from the funnel
    • Water in the residue would react with the funnel and corrode the glass
    • Water in the residue would dissolve the filter paper and spoil the result

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