A model estimates the percentage of carbon dioxide in the atmosphere and the cumulative mass of carbon stored in fossil fuels at two points in Earth's history.
| Time | Carbon dioxide in the atmosphere (%) | Carbon stored in fossil fuels (billion tonnes) |
|---|---|---|
| 2.5 billion years ago | 10 | 0 |
| 300 million years ago | 1 | 500 |
Evaluate the claim that the formation of fossil fuels was the only cause of the decrease in the percentage of carbon dioxide in the atmosphere.
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.