The table shows estimates of the relative amounts of three gases in the Earth's atmosphere at different times. The units are arbitrary.
| Time / billion years ago | Water vapour | Carbon dioxide | Oxygen |
|---|---|---|---|
| 4.4 | 100 | 80 | 0 |
| 4.0 | 10 | 30 | 0 |
| 3.0 | 10 | 25 | 0 |
| 2.0 | 10 | 10 | 1 |
Which process best explains the change in the amount of carbon dioxide between 4.4 and 4.0 billion years ago?
Photosynthesis by primitive plants, which used up the carbon dioxide in the air
Carbon dioxide dissolving in the oceans formed as water vapour condensed
Carbon dioxide reacting with oxygen in the air to form other gases
Volcanoes stopping, so that no more carbon dioxide was released
97 exam-style questions on Edexcel GCSE Chemistry 9.2 Earth and atmospheric science, covering 9.2.1 The Earth's early atmosphere, 9.2.2 How the atmosphere evolved, 9.2.3 Chemical test for oxygen, and 9.2.4 The greenhouse effect and climate change. Each one has a worked solution and a mark scheme showing where the marks go.