Cross word puzzle

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Across
  1. 3. Most abundant element in earth crust
  2. 5. Study of generalizations of arithmetic operation
  3. 9. A square matrix that is not invertible
  4. 10. To arrange information numerically/alphabetically
  5. 13. A computer virus that actively attacks an anti-virus program or programs in an effort to prevent detection is:
  6. 16. Another word for the CPU is
  7. 17. The first graphical browser for the WWW was named
  8. 18. Nuclear sizes are expressed in a unit named
Down
  1. 1. Well defined collection of distinct objects
  2. 2. Unit of Power
  3. 4. The most abundant naturally occurring gas
  4. 5. The device that measures current in a circuit
  5. 6. Bleaching action of chlorine is by
  6. 7. Computers calculate numbers in what mode?
  7. 8. Triangle with two sides of the same length?
  8. 11. The heaviest metal
  9. 12. Father of modern chemistry
  10. 14. A measure of speed in a given direction
  11. 15. The set of its possible inputs