Across
- 2. atmosphere _______ Earth
- 7. comes from decay of living things and burning
- 8. comes from volcanism and decay of living things
- 9. Atmosphere contains _____ tiny solid particles
- 10. what percent of oxygen before plants
Down
- 1. where does oxygen come from
- 3. absorbed by plants during photosynthesis
- 4. why is air more dense near earth surface
- 5. density of atmosphere
- 6. tiny liquid droplets floating in the air