Big Bang solar nebula and solar system

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Across
  1. 2. most abundant element in the universe made of most things
  2. 3. found under the Earth's crust with other natural gases
  3. 8. the chemical element of atomic number 7, a colorless, odorless unreactive gas that forms about 78 percent of the earth's atmosphere
  4. 9. a large explosion that takes place at the end of a star's life cycle
  5. 10. unification of the electromagnetic and weak nuclear interactions
  6. 13. ratio of the energy of a quantum of radiation to its frequency
  7. 14. particle of matter that defines as a chemical element
  8. 15. a dense cloud of interstellar gas and dust
Down
  1. 1. the apparent force that is felt by an object moving in a curved path that acts outwardly away from the center of rotation
  2. 4. celestial body that is in orbit around the Sun,has sufficient mass for its self-gravity to overcome rigid body force
  3. 5. trace element that is naturally present in many foods and available as a dietary supplement
  4. 6. colourless, odourless, tasteless gas essential to living organisms
  5. 7. creation of new atomic nuclei also centers of atoms that are made up of protons and neutrons
  6. 11. chemical element like hydrogen and oxygen and or any of the others in the periodic table
  7. 12. huge collection of gas, dust, and billions of stars and their solar systems