k 17

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Across
  1. 3. the number of times something happens within a particular period, or the fact of something happening often or a large number or times
  2. 5. to produce energy in a particular form
  3. 7. the process of burning
  4. 8. a pipe or channel that is used to carry away waste matter and water from a building, or an opening in the road that rain water can flow down
  5. 11. the process of converting something from one thing to another
  6. 12. a metal box containing the gears in a vehicle
  7. 14. the process of removing salt from sea water
  8. 15. the force that a liquid or gas produces when it presses against an area
Down
  1. 1. involving or produced by the heat that is inside the earth
  2. 2. any material that produces heat or power, usually when it is burnt
  3. 4. the system that keeps a building warm
  4. 6. the change of a gas to its liquid or solid form
  5. 9. the relationship between the mass of a substance and its size
  6. 10. a device that heats water, especially to provide heating and hot water in a house
  7. 13. the condition or fact of producing the results you want without waste
  8. 16. a large machine in which atoms are either divided or joined in order to produce power