CROSSWORD

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Across
  1. 4. – A pure substance made of only one type of atom.
  2. 7. – A substance made of two or more chemical elements.
  3. 9. – The smallest unit of a chemical element.
  4. 10. – An organism that gets energy by eating other organisms.
  5. 13. – The layer of gases surrounding the Earth.
  6. 15. – The relationship between the mass of a substance and its volume.
  7. 17. – A group of different species living together in an area.
  8. 18. – The ability to do work or cause change.
  9. 19. – The preservation and protection of natural resources.
Down
  1. 1. – The force that resists the movement of two surfaces in contact.
  2. 2. – The support point on which a lever pivots.
  3. 3. – A large system of stars, dust, and gas bound together by gravity.
  4. 5. – A sudden and violent shaking of the Earth's crust.
  5. 6. – An organism that eats only meat.
  6. 7. – The process where vapor turns into liquid.
  7. 8. – An organism that breaks down dead organic matter.
  8. 11. – The process in which sediment is laid down in new locations.
  9. 12. – A biological community and its physical environment.
  10. 14. – A group of stars forming a recognizable pattern.
  11. 16. – The process by which an organism adjusts to its environment.