A geologist uses carbonate sediments from ancient oceans as evidence that the Earth's early atmosphere was mainly carbon dioxide. Which is the strongest reason why this evidence is limited?
The sediments show that volcanoes released carbon dioxide, but not the proportion of nitrogen they released
The sediments show that fossil fuels stored carbon, but not which organisms formed the fuels
The sediments show that carbon dioxide entered the oceans, but not its original proportion in the atmosphere
The sediments show that photosynthesis removed carbon dioxide, but not how quickly oxygen increased
79 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.