Much of the carbon dioxide in the Earth's early atmosphere dissolved in the oceans.
Where is much of this carbon found today?
In methane gas in the atmosphere
In the Earth's molten core
In carbonate rocks such as limestone
In the water vapour in clouds
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.