chemistry

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Across
  1. 4. is a reaction in which one element is substituted for another element in a compound.
  2. 5. in a chemical reaction mass is neither created nor destroyed.
  3. 6. 6.022 x 10^23
  4. 7. is a reaction in which a substance reacts with oxygen gas, releasing energy in the form of light and heat.
Down
  1. 1. reactions that occur when two different atoms or molecules interact to form a different molecule or compound.
  2. 2. is a reaction in which the positive and negative ions of two ionic compounds exchange places to form two new compounds.
  3. 3. is a reaction in which a compound breaks down into two or more simpler substances.