Across
- 1. The layer around Earth that traps heat
- 3. Plants and animals need nitrogen to make
- 9. The most common greenhouse gas (5,6)
- 11. Summer, Autumn, Winter, ?
- 13. The hot material that erupts from volcanoes
- 15. The process that converts CO2 to O2
- 16. The first planet from the sun
- 17. The most common gas in the atmosphere
Down
- 2. When earth's tectonic plates move, ______ are caused
- 4. Over the past 200 years carbon dioxide has increased or decreased in the atmosphere
- 5. O2 is the chemical formula for
- 6. The sphere that contains rocks and soil
- 7. fossil fuels are made of this
- 8. name of the sphere with all living things
- 10. phosphorous is not found in the
- 12. A renewable source of energy that uses sunlight is known as
- 14. CH4 is the chemical formula for