Across
- 2. The amount of moisture in air is
- 4. Sound that is loud and unpleasant
- 6. capacity or ability to do work
- 8. Powerhouse of human cell
- 9. part of a plant produces most of its food
Down
- 1. gas that makes up 78 percent of the earth's atmosphere
- 3. Simple machines that use ropes or chains
- 5. The part of an atom with a negative electrical charge
- 7. the uppermost layer of the earth in which plants grow
- 8. anything that occupies space and has weight