Types of chemical reactions

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Across
  1. 4. reaction - addition of two reactants
  2. 6. - addition of oxygen
  3. 7. - addition of hydrogen
Down
  1. 1. reaction - substitution of one molecule with other molecule
  2. 2. reaction - exchange of ions
  3. 3. reaction - breakdown one molecule
  4. 5. reaction - oxidation and reduction simultaneously