Across
- 3. less visibility
- 6. situation in which something needed cannot be obtained in sufficient amounts.
- 10. a compound of nitrogen and hydrogen
- 12. a group of atoms bonded together
- 13. loosely used term for molecules present in organisms
- 14. form of dissolved nitrogen that occurs naturally in the water column
- 15. region occupied by living organisms
- 17. abnormal condition that negatively affects the structure or function of all or part of an organism
- 19. the rigid outer part of the earth
- 20. fog and smoke
- 21. air is mostly filled with
- 22. for breathing
Down
- 1. process of rotting
- 2. breathing
- 3. the action or process of fixing
- 4. plants convert light energy into chemical energy
- 5. inorganic compounds made up of nitrogen and oxygen
- 7. It is both a natural and a man-made product that occurs in the Earth's upper atmosphere (the stratosphere) and lower atmosphere (the troposphere).
- 8. introduction into the environment of a
- 9. useful or useless things thrown away
- 11. chemical used to kill pests
- 16. removes the nitrates or nitrites from (soil, air, or water) by chemical reduction.
- 18. the process of burning something.
- 20. the gaseous products of burning materials