Question 25
FA scientist analyses a mixture using gas chromatography. The diagram shows the gas chromatogram.
The table shows the retention times of five substances, measured under the same conditions.
| Substance | Retention time (min) |
|---|---|
| J | 2.0 |
| K | 4.0 |
| L | 4.5 |
| M | 6.0 |
| N | 7.5 |
Which statement is correct?
The mixture contains J, L and N. N is the most strongly attracted to the stationary phase.
The mixture contains J, L and N. J is the most strongly attracted to the stationary phase.
The mixture contains J, K and N. N is the most strongly attracted to the stationary phase.
The mixture contains J, L and N. There is most of N in the mixture, because N has the longest retention time.
2.1 Purity and separating mixtures Questions
51 exam-style questions on OCR GCSE Chemistry 2.1 Purity and separating mixtures, covering 2.1.1 Pure substances and melting point data, 2.1.2 Relative formula mass and empirical formula, 2.1.3 Formulations as useful mixtures, 2.1.4 Techniques for separating mixtures, and 2.1.5 Chromatography and Rf values. Each one has a worked solution and a mark scheme showing where the marks go.