One theory proposes that volcanoes released methane into the Earth's early atmosphere. Ancient rocks provide evidence that volcanic activity occurred at the time. Which is the best evaluation of the claim that the rocks prove methane was present?
Valid, because volcanic activity is consistent with methane being released, so the rocks establish methane was present
Not valid, because the rocks show methane was released but not whether it remained in the atmosphere
Not valid, because the rocks show volcanic activity but do not identify which gases were released
Not valid, because evidence of volcanic activity cannot support a theory that volcanoes released gases
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.