Lesson 3.3.2.1

3.3.2.1 Fractional distillation of crude oil Quiz: AQA Chemistry, Unit 3

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 3.3.2.1, Fractional distillation of crude oil: 20 multiple choice questions for the AQA Chemistry (7405), Unit 3: Organic chemistry, written with Revision Ninja.

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The 20 questions

  1. What is the main mixture that crude oil is?

    • Mainly alkenes and alkynes
    • Mainly alkane hydrocarbons
    • Mainly ionic salts
    • Pure hexane

  2. What physical property is used to separate the components of crude oil by fractional distillation?

    • Colour
    • Boiling point
    • Solubility in water
    • Electrical conductivity

  3. How does the boiling point of alkanes change as chain length increases?

    • It decreases
    • It stays the same
    • It increases
    • It falls to zero

  4. Which fraction from crude oil has the lowest boiling point and is used for bottled gas?

    • Diesel oil
    • Refinery gas
    • Bitumen
    • Lubricating oil

  5. Which fraction from fractional distillation of crude oil is the most viscous?

    • Petrol
    • Bitumen
    • Refinery gas
    • Kerosene

  6. Why is fractional distillation carried out in a column with a temperature gradient?

    • It removes all alkanes from the mixture
    • All fractions boil at the same temperature
    • The column is needed to add catalysts
    • Different fractions condense at different heights where the temperature matches their boiling points

  7. Which of these is an alkane?

    • Ethene
    • Propyne
    • Octane
    • Butene

  8. Why are alkanes described as saturated hydrocarbons?

    • They are always gaseous at room temperature
    • They contain only single carbon-carbon bonds and have the maximum number of hydrogen atoms
    • They contain a high proportion of oxygen
    • They contain double bonds that are saturated with hydrogen

  9. Which fraction of crude oil is used mainly as fuel for road vehicles?

    • Lubricating oil
    • Refinery gas
    • Bitumen
    • Petrol

  10. Which fraction of crude oil is used to make road surfaces?

    • Naphtha
    • Bitumen
    • Petrol
    • Kerosene

  11. Which alkane has the molecular formula C8H18 and is a component of petrol?

    • Propane
    • Octane
    • Decane
    • Methane

  12. What is the general formula of an alkane with 12 carbon atoms?

    • C12H28
    • C12H26
    • C12H24
    • C12H22

  13. What is the mass of one mole of octane, C8H18? (Ar: C = 12.0, H = 1.0)

    • 114 g
    • 128 g
    • 142 g
    • 98 g

  14. Which product of fractional distillation is most useful for making plastics?

    • Bitumen, because it has the most carbon atoms
    • Lubricating oil only
    • Refinery gas that is always burned as waste
    • Naphtha, as a feedstock for cracking and chemical manufacture

  15. Which fraction from the fractional distillation of crude oil is most suitable for jet engines?

    • Bitumen
    • Refinery gas
    • Kerosene
    • Lubricating oil

  16. Explain why the fractions from crude oil are separated by boiling point rather than by chemical reaction.

    • Fractional distillation chemically converts each alkane into a different compound
    • Fractional distillation separates mixtures of compounds by physical differences in boiling point, with no chemical bonds broken
    • Each fraction is separated by ionising it with electricity
    • Each fraction is separated by reacting it with a catalyst

  17. A student measures the boiling points of pentane (36 C) and hexane (69 C). Which statement best explains the difference?

    • Hexane is ionic and pentane is covalent
    • Hexane has hydrogen bonds between its molecules
    • Hexane has more electrons and stronger van der Waals forces between molecules
    • Pentane has a higher molar mass than hexane

  18. Why is crude oil described as a finite resource in the context of the alkane fractions?

    • It is formed over very long periods and cannot be replaced on a human timescale
    • It is made by industry in unlimited quantities
    • It is always replaced by biofuels
    • It contains no hydrocarbons at all

  19. A column of crude oil fractions has a temperature of 350 C at the bottom and 25 C at the top. Which fraction is collected near the top?

    • Lubricating oil
    • Bitumen
    • Heavy fuel oil
    • Refinery gas

  20. Explain why a fraction with longer chains has a higher boiling point.

    • Longer chains contain more hydrogen bonds
    • Longer chains have larger surface area for van der Waals forces, so more energy is needed to separate molecules
    • Longer chains are always ionic and attract more strongly
    • Longer chains have fewer electrons, so they are less polarisable

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