Across
- 1. process of making food (plants)
- 5. It should not be burned as it produce too much pollution
- 6. gas which has major composition in air
- 8. mixture of gases
- 10. needed for plants
Down
- 2. produced when fuel is burned
- 3. used for electricity
- 4. important for water cycle
- 7. human /animals inhale it
- 9. layer of air