A model of the early atmosphere starts with this composition by volume: water vapour 60%, carbon dioxide 24%, nitrogen 10%, sulfur dioxide 4%, other gases 2%.
In the model, all of the water vapour condenses. Then half of the carbon dioxide dissolves in the oceans. Nothing else changes.
What is the percentage by volume of carbon dioxide in the gas that remains, to 3 significant figures?
12.0%
30.0%
42.9%
60.0%
97 exam-style questions on Edexcel GCSE Chemistry 9.2 Earth and atmospheric science, covering 9.2.1 The Earth's early atmosphere, 9.2.2 How the atmosphere evolved, 9.2.3 Chemical test for oxygen, and 9.2.4 The greenhouse effect and climate change. Each one has a worked solution and a mark scheme showing where the marks go.