chem-is-try

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Across
  1. 3. heat energy from the earth
  2. 5. the gas humans need to breathe
  3. 6. the warming of the earth
  4. 7. the process by which plants make their own food
  5. 8. A gas released when fuels are burned
  6. 10. gas released during respiration
Down
  1. 1. coal, oil, and gas are called this
  2. 2. a gas produced by cows and waste
  3. 4. the process of breathing out carbon dioxide
  4. 9. cutting down many trees