A food colouring and four pure dyes were run on the same paper in the same solvent. The food colouring gave two spots.
Which pair of statements is correct?
The food colouring is pure, and the two spots are the mobile and the stationary phases
The food colouring is pure, and the second spot on the paper is the solvent front
The food colouring is a mixture, and each spot must match one of the four pure dyes
The food colouring is a mixture, and each spot may match one of the four pure dyes
40 exam-style questions on AQA GCSE Chemistry 8.1 Purity, formulations and chromatography, covering 8.1.1 Pure substances, 8.1.2 Formulations, and 8.1.3 Chromatography. Each one has a worked solution and a mark scheme showing where the marks go.