Two students discuss which process removed more carbon dioxide from the Earth's atmosphere.
Student 1 says that photosynthesis removed more carbon dioxide.
Student 2 says that the formation of sedimentary rocks and fossil fuels removed more carbon dioxide.
The table shows estimates of the mass of carbon stored in three carbon stores on the Earth today.
Table: Estimates of the mass of carbon stored in three carbon stores on the Earth today
| Carbon store | Mass of carbon / billion tonnes |
|---|---|
| Sedimentary rocks | 60 000 000 |
| Fossil fuels | 4 000 |
| Living organisms | 600 |
Give one piece of evidence that supports Student 1.
Use the table. Evaluate which of the two students is better supported by the data.
Give one reason why the values in the table are estimates.
40 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.