What this practice covers
These questions are drawn from past CIE 0620 Chemistry papers and filtered to chromatography. You answer, you find out immediately whether you were right, and you get the reasoning for the correct option and for each distractor. Wrong answers go to a mistakes locker so you can come back to exactly those.
Practice is free. You need an account only so your progress and your mistakes are still there next time.
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What examiners see students get wrong here
These are the errors that cost marks on chromatography, taken from our own topic notes. Read them before you practise and you will recognise the traps in the questions.
- Drawing the baseline in ink, so the line itself runs up the paper.
- Filling the tank so the solvent covers the spots, which dissolves them away.
- Forgetting to mark the solvent front before the paper dries.
- Measuring the substance distance to the top or bottom edge of a spot rather than to its centre.
- Measuring from the bottom of the paper instead of from the baseline.
- Dividing the solvent distance by the spot distance and reporting an Rf above 1.
- Giving Rf a unit such as cm.
- Comparing Rf values obtained in different solvents.
Revise it first
If any of the above is unfamiliar, work through the notes before practising: Chromatography revision notes.