A quality-control chemist receives a pure gas through a sampling line. Records show that the gas is hydrogen, oxygen, carbon dioxide or chlorine.
All tests are carried out on fresh small samples in a fume cupboard.
| Test | Observation |
|---|---|
| The gas is bubbled through limewater. | The limewater remains clear and colourless. |
| Damp blue litmus paper is held in the gas. | The paper remains blue. |
Explain how the results can be used to select one further test that identifies the gas. Include the observation expected for each gas that could still be present.
89 exam-style questions on AQA GCSE Chemistry 8.2 Identification of common gases, covering 8.2.1 Test for hydrogen, 8.2.2 Test for oxygen, 8.2.3 Test for carbon dioxide, and 8.2.4 Test for chlorine. Each one has a worked solution and a mark scheme showing where the marks go.