Lesson 6.3.1

6.3.1 Chromatography and qualitative analysis Quiz: OCR Chemistry, Unit 5

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 6.3.1, Chromatography and qualitative analysis: 20 multiple choice questions for the OCR Chemistry (H432), Unit 5: Organic chemistry and analysis, written with Revision Ninja.

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The 20 questions

  1. How is the Rf value calculated in thin-layer chromatography?

    • Solvent ÷ spot distance
    • Spot + solvent distance
    • Spot ÷ solvent distance
    • Spot × solvent distance

  2. What is the range of possible Rf values in one-way TLC?

    • Between 1 and 10
    • Any positive number
    • Between 0 and 1
    • Between -1 and 1

  3. In gas chromatography, what property does retention time measure?

    • Column length
    • Peak area
    • Time to detection
    • Boiling temperature

  4. What does the area under a peak in a gas chromatogram represent?

    • Molar mass
    • Retention time
    • Relative amount
    • Boiling point

  5. A spot moves 3.0 cm from the origin on a TLC plate, and the solvent front moves 6.0 cm. What is the Rf value?

    • 2.0
    • 0.33
    • 3.0
    • 0.50

  6. If an unknown and a known sample have identical retention times, what can be concluded?

    • Identical mass
    • Definitely identical
    • Structural isomers
    • May be identical

  7. A chromatogram has peak areas of 10, 30, and 60 units. What percentage is the largest peak?

    • 60%
    • 50%
    • 10%
    • 30%

  8. Which halogen is present in a haloalkane that forms a yellow precipitate with aqueous silver nitrate?

    • Iodine
    • Chlorine
    • Fluorine
    • Bromine

  9. Which reagent reacts with phenol but does not react with ethanol?

    • Sodium hydroxide
    • Sodium carbonate
    • Acidified potassium dichromate
    • Ethanoic acid

  10. Which reagent forms a silver mirror with propanal but not with propan-1-ol?

    • Tollens' reagent
    • Acidified potassium dichromate
    • Bromine water
    • Sodium carbonate

  11. Which reagent produces effervescence when added to ethanoic acid, but not ethanol?

    • Sodium carbonate
    • Tollens' reagent
    • Sodium hydroxide
    • Acidified potassium dichromate

  12. Which functional group turns acidified dichromate(VI) green but gives a negative Tollens' test?

    • Secondary alcohol
    • Aldehyde
    • Tertiary alcohol
    • Ketone

  13. What colour change is observed when bromine water is added to an alkene?

    • Orange to green
    • Orange to colourless
    • Colourless to orange
    • Brown to purple

  14. Which haloalkane reacts fastest with aqueous silver nitrate in ethanol when warmed?

    • 1-chlorobutane
    • 1-fluorobutane
    • 1-bromobutane
    • 1-iodobutane

  15. What feature of a gas chromatogram is directly proportional to component concentration?

    • Retention time
    • Peak width
    • Baseline height
    • Peak area

  16. What is the stationary phase in thin-layer chromatography?

    • Liquid solvent
    • Silica gel layer
    • Mobile solvent
    • Carrier gas

  17. A gas chromatogram shows a peak with area 40 out of a total area of 160 units. What proportion of the mixture is this component?

    • 25 per cent
    • 40 per cent
    • 4 per cent
    • 16 per cent

  18. A TLC spot is 2.0 cm from the origin and the solvent front is 8.0 cm from the origin. What is the Rf value?

    • 0.75
    • 0.25
    • 4.0
    • 0.40

  19. Why is pencil used instead of ink to draw baselines in thin-layer chromatography?

    • Pencil is cheaper
    • Ink reacts chemically
    • Pencil sticks better
    • Ink dissolves

  20. What can be concluded if an unknown and a reference compound have identical Rf values?

    • Definitely identical compounds
    • Potentially identical compounds
    • Incorrect solvent choice
    • Different chemical structures

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