Question 5
FThe graph shows estimates of the percentages of three gases in the Earth's atmosphere over time.
Which conclusion about the period from 4.0 to 2.0 billion years ago is best supported by the graph?
Photosynthesis removed most of the carbon dioxide lost in this period, because the percentage of oxygen increased at the same time.
Most of the carbon dioxide lost in this period was removed by processes other than photosynthesis, such as dissolving in the oceans.
The percentage of carbon dioxide decreased at a steady rate throughout this period.
The percentage of nitrogen increased because carbon dioxide was converted into nitrogen.
6.3 Interpreting and interacting with earth systems Questions
51 exam-style questions on OCR GCSE Chemistry 6.3 Interpreting and interacting with earth systems, covering 6.3.1 Formation and evolution of the atmosphere, 6.3.2 The greenhouse effect and climate change, 6.3.3 Sources and problems of atmospheric pollutants, and 6.3.4 Producing potable water. Each one has a worked solution and a mark scheme showing where the marks go.