# A student carries out paper chromatography on a sample of black ink and on a pure dye called Dye X. The black ink produces four separate spots on the paper. Dye X produces only one spot, and its spot appears at the same position as one of the spots from the black ink. Explain what these results tell us about the black ink and about Dye X.

> Eduqas GCSE Chemistry — 1.5 Rate of chemical change · Explain · 4 marks

## Mark scheme (4 marks)

1. Black ink is a mixture (not a pure substance)
2. The four spots show that black ink contains four different substances / compounds / dyes
3. Dye X is a pure substance because it produces only one spot
4. Dye X is one of the components / dyes present in the black ink, because its spot is at the same position / has the same Rf value

## Key terms

- [paper chromatography](https://www.gradenine.co.uk/glossary/paper-chromatography)

## Related

- [Revision notes for Eduqas GCSE Chemistry](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/a-student-carries-out-paper-chromatography-a0a1b697) · Published by Druglandscape Ltd.