Test 4 - BONUS

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Across
  1. 7. atoms that have a nucleus that is unstable and decomposes spontaneously
  2. 9. heat within the earth
  3. 10. measurement of the rate of decomposition for any given isotope
Down
  1. 1. the process of splitting the nucleus of an atom that is "fissionable"
  2. 2. resources that are used much faster than they can be produced; amount is limited
  3. 3. clean, renewable energy source
  4. 4. solid-state semiconductor devices that convert light directly into electricity
  5. 5. replenish themselves as a continuously present feature of the solar system
  6. 6. light energy is transformed to heat energy when it is absorbed by a surface
  7. 8. requires a solar collector, a pump and a system of pipes to transfer heat from the site of production to the area to be heated