Across
- 3. decomposition of plants and animals burned for energy
- 6. compound released when we breath out
- 9. mixture of gases that surround the earth
- 10. element released during photosynthesis
- 11. gas produced by livestock
- 12. the lightest of the three states of matter
- 13. when underwater plants turn white
- 14. contamination of the environment with harmful substances
Down
- 1. discharge of a substance
- 2. power from natural resources
- 4. H2O in gas form
- 5. what we breath
- 7. mass removal of trees
- 8. humid home for plants
- 13. the basic element of all life on earth