Across
- 2. added to gasoline to make engines run smoothly
- 4. the process by which petroleum is made into different products
- 5. the type of coal that is most abundant in the US
- 7. a compound that contains only hydrogen and carbon
- 9. the first type of true coal
- 12. the hardest type of coal
- 13. a solid fossil fuel
- 14. a brown, brittle plant material with a low % of carbon
- 15. a substance from which energy can be obtained
Down
- 1. used for barbecues
- 3. both coal and __________ are forms of carbon
- 6. fossil fuels are_________________
- 8. another name for crude oil
- 10. this gas is often trapped with petroleum
- 11. used to heat our homes