A mixture M is compared with four dyes, P, Q, R and S, using two different solvents. M gives two spots in each solvent.
| Substance | Rf R_f\,Rf in solvent 1 | Rf R_f\,Rf in solvent 2 |
|---|---|---|
| M | 0.30 and 0.72 | 0.20 and 0.55 |
| P | 0.30 | 0.20 |
| Q | 0.72 | 0.55 |
| R | 0.30 | 0.64 |
| S | 0.72 | 0.41 |
Which dyes are in mixture M?
P and S
Q and R
R and S
P and Q
107 exam-style questions on Edexcel GCSE Chemistry 3.2 Methods of separating and purifying substances, covering 3.2.1 Pure substances and mixtures, 3.2.2 Techniques for separating mixtures, 3.2.3 Paper chromatography and Rf values, and 3.2.4 Making water potable. Each one has a worked solution and a mark scheme showing where the marks go.