Lesson 5.8.1.1

5.8.1.1 Pure substances Quiz: AQA Combined Science, Unit 15

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 5.8.1.1, Pure substances: 20 multiple choice questions for the AQA GCSE Combined Science (8464), Unit 15: Chemical analysis, written with Revision Ninja.

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The 20 questions

  1. In chemistry, what defines a pure substance?

    • Substance containing water
    • Single element or compound
    • Filtered liquid solution
    • Natural unadulterated mixture

  2. At what temperatures do pure elements and compounds melt and boil?

    • At random temperatures
    • Specific temperatures
    • Only above 1000 degrees
    • Over a wide range

  3. What can melting point data be used to determine about a substance?

    • Purity
    • Colour
    • pH value
    • Density

  4. In everyday language, what does a pure substance mean?

    • Filtered liquid
    • Chemically bonded
    • Nothing added
    • Single element

  5. What happens to the boiling point of a salt solution?

    • Stays at 100 degrees C
    • Decreases steadily
    • Boils instantly
    • Boils over a range

  6. Which data is used to test the purity of a substance?

    • Container colour
    • Melting point
    • Total mass
    • Volume

  7. A sample melts over a range of 5 degrees C. It is most likely:

    • Pure
    • A single compound
    • An element
    • Impure

  8. A sample of water boils at 102 degrees C. What is it?

    • Pure compound
    • Pure element
    • Single atom
    • Impure

  9. What indicates that a solid chemical sample is pure?

    • Slow dissolving
    • Melting range
    • Sharp melting point
    • Multiple colours

  10. Which is a pure substance in the chemistry sense?

    • Air in a room
    • Sea water, salty
    • Distilled water
    • Fresh cow's milk

  11. What does a chemical definition of a pure element consist of?

    • Multiple mixed compounds
    • Any unadulterated liquid
    • One type of atom
    • Two bonded elements

  12. A substance boils at 78 degrees C consistently. This is consistent with:

    • A definite mixture
    • An impossible result
    • A pure substance
    • A formulation

  13. Adding salt to ice makes the ice melt at:

    • A higher temperature
    • The same temperature
    • A lower temperature
    • Exactly zero degrees

  14. An impure sample's melting point compared with the pure compound's is:

    • Lower
    • The same
    • Higher
    • Undefined

  15. What temperature range does a liquid mixture boil at?

    • A fixed sharp point
    • Absolute zero
    • Room temperature only
    • A range of temperatures

  16. What is the best evidence that a liquid sample is pure water?

    • Neutral pH
    • High volume
    • Fixed boiling point
    • Clear colour

  17. In chemistry, what is a pure substance defined as?

    • Solution of one solvent
    • Natural healthy food
    • Mixture without additives
    • Single element or compound

  18. Why do pure elements melt at a fixed temperature?

    • Unstable bonds
    • Identical particles
    • Mixed molecules
    • Variable masses

  19. Which sample will give a sharp, fixed boiling point?

    • Paint solution
    • Tap water
    • Pure liquid compound
    • Alloy mixture

  20. Why might a pure liquid boil at an unexpected temperature?

    • Incorrect thermometer type
    • Too much volume
    • Pressure variation
    • Extra cooling applied

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