Earth's Atmosphere

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Across
  1. 3. Made the Earth richer in oxygen
  2. 4. Taken in by plants through Photosynthesis
  3. 7. 78% of Earth's Atmosphere
  4. 8. The most abundant noble gas found in the air
Down
  1. 1. A carbon 'sink'
  2. 2. Turned into rain when the Earth cooled
  3. 5. 21% of Earth's Atmosphere
  4. 6. Fossil fuel formed from grazing cattle