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Across
  1. 3. A substance that speeds up a chemical reaction without getting consumed
  2. 4. A reaction that produces heat and light, often involving combustion
  3. 6. gain of electrons in an atom or the gain of hydrogen and the removal of oxygen.
  4. 7. The process in which substances react to form new substances
Down
  1. 1. ffnm
  2. 2. The method of representing a chemical reaction with symbols and formulas
  3. 3. The number written before a formula in a chemical equation to balance it
  4. 5. The substance that is produced in a chemical reaction