Across
- 1. Chemical formula for carbon dioxide
- 3. A gas that is produced by animals such as cows
- 6. The name given to the chemical with the formula NH3
- 7. Water in a gaseous state
- 12. A gas that can be used in the treatment of water
- 14. In human terms, ____ are materials we get from the environment to meet our needs
- 15. A substance that can be used in a fuel cell to power cars and other automobiles
- 19. In some parts of the world, seawater is made drinkable by ____?
- 20. Name of the element with the symbol C
- 21. Another name for calcium carbonate
- 23. Term used for describing a chemical reaction that releases heat
- 24. The process by which a solid may be transformed directly to a gas without passing through a liquid state
Down
- 2. Name of the element with the symbol O
- 4. A chemical substance that is added to fertilisers that provides plants with nitrogen
- 5. A gas found in air with a boiling point of approximately -196 degrees Celcius
- 8. Name of the element with the symbol Cl
- 9. Chemical formula for nitrogen dioxide
- 10. A neurotoxic metal
- 11. The process by which plants absorb H2O and CO2 to form sugar and oxygen (with the help of sunlight and a catalyst)
- 13. A noble gas with a boiling point of approximately -108 degrees Celcius
- 16. Catalytic converters may be attached to the ____ systems of cars
- 17. A type of fossil fuel
- 18. The distance from the earth's surface to its ____ is over 6000 km
- 22. Another name for calcium oxide
- 25. Water in a frozen state