A factory makes a cleaning fluid that should contain heptane and no other substance. A quality-control laboratory analyses four batches by gas chromatography. The reference solvents and the batches are analysed under the same conditions.
| Reference solvent | Retention time in minutes |
|---|---|
| Pentane | 1.4 |
| Hexane | 2.3 |
| Heptane | 3.6 |
| Octane | 5.2 |
| Batch | Retention times of peaks in minutes |
|---|---|
| P | 1.4, 3.6 |
| Q | 3.6 |
| R | 2.3 |
| S | 3.6, 5.2 |
Which batch meets the factory's requirement?
Batch P
Batch Q
Batch S
Batch R
107 exam-style questions on OCR GCSE Chemistry 4.2 Identifying the products of chemical reactions, covering 4.2.1 Tests to identify gases, 4.2.2 Tests for aqueous ions and flame tests, and 4.2.3 Instrumental methods of analysis. Each one has a worked solution and a mark scheme showing where the marks go.