Science crossword puzzle.

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Across
  1. 3. H2O
  2. 5. Chemically bound.
  3. 6. Multiple atoms chemically bound together.
  4. 9. Most abundant metal on earth.
  5. 10. You're made of it.
Down
  1. 1. C
  2. 2. Never trust.
  3. 4. Na
  4. 7. All the same atoms.
  5. 8. Can be separated without a chemical reaction.