My puzzle (easy)

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Across
  1. 3. capital of egypt
  2. 4. a scream
  3. 7. pyramids of
  4. 9. language in brazil
  5. 12. number of planets in our solar system
  6. 14. true color of the sun
  7. 16. thor's father
  8. 17. the thomas of light bulbs
  9. 18. greek goddess of wisdom
Down
  1. 1. red hair
  2. 2. capital of spain
  3. 5. red and blue
  4. 6. highest point
  5. 8. famous author christie
  6. 10. symbol of silver
  7. 11. symbol Br
  8. 13. second weekday
  9. 15. a place to tweet