Lesson T3.1.2

T3.1.2 Mixtures and dissolving Quiz: KS3 Chemistry, Unit 3

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson T3.1.2, Mixtures and dissolving: 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 a solution?

    • A gas that has no particles and so cannot be seen or weighed at all
    • A compound made of a solid and a liquid that cannot be separated by filtration
    • A pure substance made of one element that is always a liquid at room temperature
    • A mixture in which a solute dissolves in a solvent

  2. Which is the solvent in salt water?

    • Water
    • Sodium chloride crystals
    • Salt
    • Chlorine gas

  3. Which substance is the solute when sugar is dissolved in tea?

    • Milk
    • Sugar
    • Tea
    • Water

  4. What happens to the particles of a solute when it dissolves?

    • They spread out evenly among the solvent particles
    • They separate into electrons and protons
    • They are destroyed and turn into energy
    • They react to form a new compound with the solvent

  5. Why does sugar dissolve faster in warmer water?

    • Sugar particles get bigger in warm water, which makes them dissolve more quickly
    • Warm water has fewer particles than cold water, so the sugar meets less water
    • Warm water is heavier than cold water, so it pulls the sugar down more quickly
    • Warmer water particles have more energy, so they collide with sugar more often

  6. Which of these would NOT be a mixture?

    • Sand mixed with water
    • Salt dissolved in water
    • Air, which is a mixture of gases
    • Pure distilled water

  7. Which of these can be dissolved in water to make a solution?

    • Chalk
    • Iron filings
    • Sand
    • Salt

  8. A student adds sand to water and stirs it for a long time. It settles at the bottom. What is the correct description?

    • A pure substance with a fixed boiling point that depends on the amount of sand
    • A compound formed when sand reacts with water to make a new substance
    • A mixture that is not a solution, because the sand does not dissolve
    • A solution, because the sand has dissolved fully and cannot be seen any more

  9. Coffee granules are stirred into hot water and all of them dissolve. What is the mixture?

    • A solution
    • A suspension of solid particles
    • A pure element
    • A compound

  10. Why do solids that dissolve in water appear to disappear?

    • Their particles are heavier than water and sink through it to the bottom
    • Their particles become energy and leave the water as a faint warm vapour
    • Their particles change into a gas and float up out of the water over time
    • Their particles spread between the water particles and are too small to see

  11. Which of these is a suspension rather than a solution?

    • Salt water with all of the salt dissolved fully in the water and clear
    • Sugar water with no solid visible, because the sugar has dissolved completely
    • Muddy water, with soil particles that settle out
    • Air as a mixture of nitrogen and oxygen gases that is spread evenly

  12. A salt solution is left in an open dish. After several days, salt crystals are seen. What process happened?

    • The salt melted into a liquid
    • The water evaporated and left the salt behind
    • The salt reacted with the dish to form crystals
    • The salt dissolved again into the air

  13. Which word describes a substance that dissolves in a solvent?

    • A catalyst
    • A residue
    • A solute
    • A solvent

  14. Why is a mixture of sugar and water called a solution?

    • The sugar floats on top of the water in a layer that can be skimmed off
    • The water has turned into a gas and the sugar has been left in the air
    • The sugar is evenly spread throughout the water and cannot be seen
    • The sugar and water have reacted to form a new compound with a fixed ratio

  15. Which factor would increase how quickly a solid dissolves in a liquid?

    • Keeping the mixture still with no stirring so the solid can settle at the bottom
    • Using a larger lump of solid so that more surface meets the water at once
    • Stirring the mixture, which brings fresh solvent to the solid
    • Using a colder solvent, because cold particles collide more often with the solid

  16. Which is true of a saturated solution?

    • Solute can be removed by filtration only, and it cannot be recovered by heating
    • Solute will dissolve endlessly in the same solvent without any limit at all
    • No more solute will dissolve at that temperature
    • The solvent has turned into a solid that traps the remaining solute inside it

  17. What happens to the mass of salt when salt dissolves in water and the water is not evaporated?

    • It becomes lighter than before because some of it has turned into a gas
    • It turns into water and no longer counts as part of the total mass at all
    • It is still present in the solution, so total mass is the same
    • It disappears completely from the mixture and cannot be recovered afterwards

  18. A mixture of sand, salt and water is made. Which statement is correct?

    • The sand and salt can only be separated by a magnet, because both are solids
    • The sand can be separated by filtering, and the salt by evaporating the water
    • The mixture can be separated only by heating it to 1000 °C in a furnace
    • The salt and water are separated by filtration, which removes the dissolved salt

  19. A student dissolves 10 g of salt in 100 cm³ of water. What is the water here?

    • The product
    • The solvent
    • The solute
    • The residue

  20. What is the greatest mass of solute that can dissolve in a fixed volume of solvent at a set temperature?

    • Density
    • Boiling point
    • Solubility
    • Melting point

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