air and water

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Across
  1. 1. lead compounds are ......, which cause several health issues such as lung disease
  2. 4. sulfur dioxide causes ...... which kills plants and aquatic life, erodes stonework, corrodes metals
  3. 8. lead compounds are formed from ... petrol
  4. 9. ..... is used on a global scale, so these problems affect the whole world
  5. 11. other gas that makes up air, but not noble gases
  6. 13. in the separation of nitrogen and oxygen, air is first .....
  7. 15. gas that makes up 78 % of air
  8. 17. oxides of nitrogen react with other pollutants, in ........, to form a photochemical smog, which causes breathing difficulties
  9. 18. fuels sulfur dioxide is formed from combustion of ...... which contain sulfur compounds
  10. 21. oxides of nitrogen is formed from ....
  11. 22. the temperature is increased until oxygen boils and .... to the top as a gas and is collected
Down
  1. 2. .....converters are used to remove oxides of nitrogen
  2. 3. Nitrogen and carbon dioxide are relatively .....gases
  3. 5. Carbon monoxide + .... -> nitrogen + carbon dioxide
  4. 6. carbon monoxide is formed from .... combustion of carbon - containing fuels
  5. 7. what are carbon monoxide, sulfur dioxide, oxides of nitrogen, and lead compounds?
  6. 10. gas that makes up 21% of air
  7. 12. fractional distillation column temperature is increased until nitrogen .....and rises to the top as a gas, and collected
  8. 14. oxygen and nitrogen can be separated from liquid air by .... distillation
  9. 16. oxygen has a boiling point ....than that of nitrogen
  10. 19. poisonous carbon monoxide causes .......difficulties, because it reduces the amount of oxygen that red blood cells can carry around the body
  11. 20. oxides of nitrogen also cause ..... rain