Lesson 19C.1

19C.1 Chromatography and Rf values Quiz: Pearson Edexcel Chemistry, Unit 19

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 19C.1, Chromatography and Rf values: 20 multiple choice questions for the Pearson Edexcel Chemistry (9CH0), Unit 19: Modern Analytical Techniques II, written with Revision Ninja.

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The 20 questions

  1. What is the Rf value if a spot travels 3.0 cm and the solvent front travels 6.0 cm?

    • 0.25
    • 2.0
    • 0.50
    • 3.0

  2. What acts as the stationary phase in standard paper chromatography?

    • Dry cellulose paper
    • Liquid solvent
    • Mobile organic phase
    • Water on cellulose

  3. What is the stationary phase in silica thin-layer chromatography (TLC)?

    • Liquid solvent
    • Silica gel
    • Plastic backing
    • Carrier gas

  4. Why is the baseline line in paper chromatography drawn in pencil instead of ink?

    • Pencil absorbs solvent
    • Ink is invisible
    • Pencil is insoluble
    • Ink is non-polar

  5. Why must the solvent level be below the origin line in TLC?

    • Stops baseline burning
    • Increases Rf values
    • Prevents spots dissolving
    • Prevents solvent evaporating

  6. A spot travels 4.2 cm and the solvent front travels 7.0 cm. What is the Rf value?

    • 0.60
    • 1.67
    • 0.42
    • 0.70

  7. A spot travels 2.5 cm and the solvent front travels 10.0 cm. What is the Rf value?

    • 0.75
    • 4.00
    • 0.25
    • 0.40

  8. Matching Rf values of an unknown compound and a standard under identical conditions suggests what?

    • Possible identity
    • Different structures
    • High purity
    • Definite identity

  9. What state is the mobile phase in high performance liquid chromatography (HPLC)?

    • Low-pressure gas
    • High-pressure liquid
    • High-pressure gas
    • Solid gel

  10. What is used as the mobile phase in gas chromatography (GC)?

    • Finely divided solid
    • Unreactive carrier gas
    • Polar liquid solvent
    • Non-polar liquid solvent

  11. What causes different components to separate as they pass through a chromatography column?

    • Different phase interactions
    • Different flow rates
    • Different column lengths
    • Different particle sizes

  12. What is the main function of the mass spectrometer in a combined GC-MS system?

    • Injecting samples
    • Separating components
    • Identifying components
    • Vaporising samples

  13. A component with a longer retention time in gas chromatography has a greater affinity for which phase?

    • Solvent front
    • Carrier gas
    • Mobile phase
    • Stationary phase

  14. Changing the solvent in thin-layer chromatography changes Rf values by altering what property?

    • Phase partitioning
    • Molar mass
    • Stationary phase thickness
    • Sample boiling point

  15. In thin-layer chromatography, a spot with a higher Rf value has a greater affinity for which phase?

    • Absorbent phase
    • Stationary phase
    • Solid phase
    • Mobile phase

  16. A spot moves 3.6 cm and the solvent front moves 8.0 cm. What is the Rf value?

    • 0.55
    • 2.22
    • 0.36
    • 0.45

  17. In gas chromatography, a compound with a retention time of 6.8 minutes compared to 4.2 minutes is what?

    • Of lower mass
    • More volatile
    • Moving more quickly
    • Retained for longer

  18. Why must Rf values always be quoted alongside the solvent and stationary phase?

    • Mass dependent
    • Condition dependent
    • Always constant
    • Temperature independent

  19. An Rf value of 1.0 indicates that a compound has zero affinity for which phase?

    • Liquid phase
    • Solvent phase
    • Mobile phase
    • Stationary phase

  20. An Rf value of 0.0 indicates that a compound has zero affinity for which phase?

    • Solid phase
    • Mobile phase
    • Column phase
    • Stationary phase

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