In The proportions of different gases in the atmosphere, which option helps you define the chemistry term precisely: Recall that the Earth's atmosphere contains small proportions of other gases including carbon dioxide, water vapour and noble gases?

The correct option is Water vapour. For this definition question, that option is correct because it matches Recall that the Earth's atmosphere contains small proportions of other gases including carbon dioxide, water vapour and noble gases in The proportions of different gases in the atmosphere.

Water vapour is the correct answer for this AQA GCSE Chemistry atmosphere question. Start from the exact meaning, then reject any option that only names a related gas. The learning objective is: Recall that the Earth's atmosphere contains small proportions of other gases including carbon dioxide, water vapour and noble gases. In The composition and evolution of the Earth's atmosphere, this means the explanation must use the subtopic The proportions of different gases in the atmosphere and avoid drifting into a different gas, pollutant, climate, or early-atmosphere idea. Checkpoint 17: this page uses the definition angle so students can practise one distinct reasoning route before moving to the next question.