AIR

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Across
  1. 2. used in incandescent light bulbs
  2. 4. used in red lighting in signs
  3. 5. gas released by grazing cattle, marshlands and rice fields
  4. 7. when the air becomes contaminated
  5. 8. needed by living organisms for respiration
  6. 9. gas used to inflate balloons and blimps
Down
  1. 1. place in the cell where respiration takes place
  2. 3. this term means the gas is unreactive
  3. 6. the most abundant gas in air