A student tests three liquid samples. The results are shown in the table.
| Sample | Boiling point (∘C^\circ\mathrm{C}∘C) | Solid left after evaporation |
|---|---|---|
| P | 100 | None |
| Q | 100 | White solid |
| R | 99 | None |
Identify which sample is pure water. Use both sets of results to support your answer.
109 exam-style questions on OCR GCSE Chemistry 6.3 Interpreting and interacting with earth systems, covering 6.3.1 Formation and evolution of the atmosphere, 6.3.2 The greenhouse effect and climate change, 6.3.3 Sources and problems of atmospheric pollutants, and 6.3.4 Producing potable water. Each one has a worked solution and a mark scheme showing where the marks go.