A gas-separation unit processes 1000 dm3 of clean, dry air. The table shows the percentage of each gas that the unit removes from the air.
Ignore the other gases in air.
| Gas | Percentage of the gas removed by the unit |
|---|---|
| Nitrogen | 75% |
| Oxygen | 50% |
Use your knowledge of the composition of air to calculate the volume of each gas that remains after the air has passed through the unit.
A student says:
“Because oxygen has been removed, the percentage of oxygen in the gas must have decreased.”
Explain why the student's statement is not correct.
79 exam-style questions on AQA GCSE Chemistry 9.1 The composition and evolution of the Earth's atmosphere, covering 9.1.1 The proportions of different gases in the atmosphere, 9.1.2 The Earth's early atmosphere, 9.1.3 How oxygen increased, and 9.1.4 How carbon dioxide decreased. Each one has a worked solution and a mark scheme showing where the marks go.