Lesson 4.8.1.1

4.8.1.1 Pure substances Quiz: AQA Chemistry, Unit 8

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 4.8.1.1, Pure substances: 20 multiple choice questions for the AQA GCSE Chemistry (8462), Unit 8: Chemical analysis, written with Revision Ninja.

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The 20 questions

  1. In chemistry, what defines a pure substance?

    • A uniform alloy
    • Single element or compound
    • A natural mixture
    • Unfiltered tap water

  2. How do pure elements and compounds melt and boil?

    • High pressures
    • Low volumes
    • Specific temperatures
    • Variable ranges

  3. Which physical data can distinguish pure substances from mixtures?

    • Melting point
    • Colour intensity
    • Sample mass
    • Total volume

  4. Which of these is a pure substance in chemistry?

    • Milk
    • Distilled water
    • Air
    • Seawater

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

    • Natural state
    • Unfiltered liquid
    • Single element
    • Fixed compound

  6. What does a substance melting over a wide temperature range indicate?

    • It is impure
    • It is a metal
    • It is an element
    • It is pure

  7. Which substance would have a sharp, fixed boiling point?

    • Pure ethanol
    • Air
    • Seawater
    • Crude oil

  8. How are elements arranged within a pure compound?

    • Random mixture
    • Variable proportions
    • Physical blend
    • Fixed ratio

  9. A sample melts sharply at 0 °C. What is the sample?

    • Salty water
    • Pure water
    • Impure ice
    • A liquid mixture

  10. A liquid boils from 80 degrees Celsius to 100 degrees Celsius. What does this suggest?

    • It is an element
    • It is a pure solvent
    • It is impure
    • It is pure

  11. Which result best supports the conclusion that a substance is pure?

    • Melting range
    • Sharp melting point
    • Gradual softening
    • Variable boiling point

  12. Sample A boils at a single temperature of 118 °C. Sample B boils across 65 °C to 95 °C. Which is more likely pure?

    • Sample A
    • Neither
    • Both equally pure
    • Sample B

  13. Which everyday item is scientifically classified as a mixture rather than a pure substance?

    • Water
    • Milk
    • Gold
    • Oxygen

  14. A liquid has a fixed boiling point of 100 °C every time. What is it likely to be?

    • Pure water
    • Sea water
    • Salt solution
    • Pure milk

  15. What property is used to distinguish between pure substances and mixtures?

    • Mass
    • Volume
    • Colour
    • Melting point

  16. Which of these substances would boil over a range of temperatures rather than a single value?

    • Pure copper
    • Salt solution
    • Ethanol
    • Pure water

  17. Why does a liquid mixture boil over a range of temperatures?

    • Identical components
    • Fixed melting point
    • Constant pressure
    • Different boiling points

  18. What effect does dissolving salt in water have on its freezing point?

    • No effect
    • Lowers freezing point
    • Raises freezing point
    • Removes freezing point

  19. Which observation confirms a solid sample is a pure compound?

    • Fixed melting point
    • Gradual melting
    • Variable melting
    • Melting range

  20. How does the melting behaviour of a pure substance differ from a mixture?

    • Melting range
    • Higher mass
    • Fixed temperature
    • Variable points

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