An environmental laboratory receives four gas samples, P, Q, R and S, in gas-tight bags. Each sample contains hydrogen, oxygen, carbon dioxide or chlorine. A gas may be present in more than one sample.
A technician transfers a small portion of each sample to a test tube and records the results.
| Sample | Test | Result |
|---|---|---|
| P | a burning splint is held at the open end of the test tube | a squeaky pop is heard |
| Q | a glowing splint is lowered into the test tube | the splint relights |
| R | the gas is bubbled through limewater | the limewater turns cloudy |
| S | dry blue litmus paper is held in the gas | no visible change |
Name the gas in samples P, Q and R.
A technician concludes that sample S cannot be chlorine. Evaluate the technician's conclusion. Include a suitable test for chlorine in your answer.
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.