Oxygen and Carbon Dioxide

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Across
  1. 4. The chemical process of burning
  2. 5. The hot, glowing part of a fire
  3. 9. A substance that is used up during a chemical reaction
  4. 10. A gas that supports combustion and is needed for respiration
  5. 11. The amount of a substance present in a mixture
  6. 12. The mixture of gases that surrounds us
  7. 14. Substances that can be burned to release energy
  8. 16. A device used to put out a fire
  9. 18. The process of breathing air into the lungs
  10. 20. The process cells use to release energy from food
  11. 21. To cause a fire to stop burning
Down
  1. 1. A substance formed during a chemical reaction
  2. 2. The ability of a substance to burn
  3. 3. A state of matter that spreads out to fill its container
  4. 5. A substance that can be burned to release energy
  5. 6. Relating to electricity or electric current
  6. 7. dioxide A gas produced during respiration and breathed out by animals
  7. 8. A process in which substances are changed into new substances
  8. 13. The layer of gases surrounding Earth
  9. 14. Able to catch fire and burn easily
  10. 15. To breathe air out of the lungs
  11. 17. A chemical reaction involving oxygen
  12. 19. The process of starting combustion