1) Amount of carbon dioxide in today's atmosphere a) 0.9% b) 21% c) 0.04% d) 78% 2) A process that uses carbon dioxide and produces oxygen a) photosynthesis b) respiration 3) How the oceans formed a) Water evaporated as the Earth cooled b) Water vapour condensed as the Earth cooled 4) Amount of oxygen in today's atmosphere a) 78% b) 21% c) 0.9% d) 0.04% 5) Where the Earth's original atmosphere came from a) oceans b) volcanoes c) earthquakes d) space 6) Two main gases in Earth's original atmosphere a) nitrogen and oxygen b) oxygen and carbon dioxide c) nitrogen and water vapour d) carbon dioxide and water vapour 7) Where most of the original carbon dioxide went a) Became dissolved in the oceans b) Was used by animals and plants for respiration 8) Amount of nitrogen in today's atmosphere a) 21% b) 78% c) 0.9% d) 0.04% 9) A process that uses oxygen and produces carbon dioxide a) photosynthesis b) respiration

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