Lesson 5.7.1.3

5.7.1.3 Properties of hydrocarbons Quiz: AQA Combined Science, Unit 14

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 5.7.1.3, Properties of hydrocarbons: 20 multiple choice questions for the AQA GCSE Combined Science (8464), Unit 14: Organic chemistry, written with Revision Ninja.

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The 20 questions

  1. As molecular size increases, boiling point:

    • Becomes zero
    • Increases
    • Decreases
    • Stays the same

  2. As molecular size increases, viscosity:

    • Increases
    • Stays the same
    • Decreases
    • Reverses

  3. As molecular size increases, flammability:

    • Increases
    • Stays the same
    • Is always explosive
    • Decreases

  4. What energy change occurs during the combustion of hydrocarbon fuels?

    • Keeps energy constant
    • Stores thermal energy
    • Absorbs energy
    • Releases energy

  5. During combustion, the carbon and hydrogen in fuels are:

    • Oxidised
    • Neutralised
    • Reduced
    • Precipitated

  6. What are the two products of complete hydrocarbon combustion?

    • Carbon monoxide and water
    • Carbon dioxide and water
    • Methane and oxygen
    • Carbon and hydrogen

  7. Which property is NOT among the limited trends you need to know?

    • Flammability
    • Boiling point
    • Colour
    • Viscosity

  8. Propane is burned completely: C3H8 + ___ O2 gives 3CO2 + 4H2O. The number is:

    • 10
    • 5
    • 4
    • 3

  9. In complete combustion of butane (C4H10), the number of CO2 molecules formed per butane is:

    • 10
    • 4
    • 5
    • 8

  10. In complete combustion of methane, CH4 + 2O2 gives CO2 + ___ H2O. The number is:

    • 4
    • 1
    • 3
    • 2

  11. Balance: 2C2H6 + ___ O2 gives 4CO2 + 6H2O. The number is:

    • 7
    • 14
    • 3
    • 6

  12. Pentane (C5H12) burns completely with 8 O2 per molecule. Check the oxygen count with 5 CO2 and 6 H2O: the O2 number is:

    • 16
    • 5
    • 8
    • 6

  13. The products of complete combustion of pentane are:

    • CO2 and H2
    • CO and H2O
    • C and H2O
    • CO2 and H2O

  14. Hexane (C6H14) burns completely: the number of H2O molecules per hexane is:

    • 3
    • 6
    • 7
    • 14

  15. Octane (C8H18) burns completely: the number of CO2 molecules per octane is:

    • 16
    • 9
    • 8
    • 18

  16. A heavier alkane flows more slowly. Which property does this show?

    • Viscosity
    • Colour
    • Boiling point
    • Flammability

  17. Which fuel is most flammable among petrol, diesel and heavy fuel oil?

    • Heavy fuel oil
    • Paraffin wax
    • Bitumen
    • Petrol

  18. Why do heavier hydrocarbons have higher boiling points?

    • Faster molecular speed
    • Stronger intermolecular forces
    • Higher electrical charge
    • Stronger covalent bonds

  19. Which equation shows complete combustion of methane?

    • CH4 + 2O2 gives CO + 2H2O
    • CH4 gives C + 2H2
    • CH4 + O2 gives CO2 + H2
    • CH4 + 2O2 gives CO2 + 2H2O

  20. Which observation shows that a hydrocarbon fuel releases energy?

    • Temperature rise
    • pH decrease
    • Volume contraction
    • Colour fading

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