Oxygen is one of the gases in the Earth’s atmosphere today. The percentage of oxygen in the Earth’s atmosphere has changed significantly over geological time.
Which row in the table shows the approximate percentage of oxygen thought to be present in the Earth’s early atmosphere and how this percentage changed over time to form the atmosphere we have today?
| Approximate percentage of oxygen in the early atmosphere | Change in oxygen percentage over time to today | |
|---|---|---|
| A | < 1% | increased |
| B | < 1% | decreased |
| C | 21% | increased |
| D | 21% | decreased |
Row A
Row B
Row C
Row D
Practise Edexcel GCSE Chemistry Earth and atmospheric science with exam-style questions for Foundation and Higher tier. 62 questions, matched to the Edexcel GCSE Chemistry (1CH0) specification and written in Paper 1 and Paper 2 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.
