I am a Gas!

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Across
  1. 2. I am a noble gas, and I emit a brilliant reddish-orange color in advertising signs.
  2. 4. I am a noble gas, and I'm used to fill up party balloons and blimps.
  3. 6. I am a gas that is vital for life on Earth. We can't live without it.
  4. 8. I make up 78 percent of the Earth's atmosphere.
  5. 9. I am a noble gas, and I'm used for arc welding and fluorescent lights.
  6. 10. I am a noble gas, and I'm used in flashlights and photographic flashes.
Down
  1. 1. I am a halogen, and I'm used to clean my teeth, and eliminate cavities.
  2. 3. Without me, humans cannot survive, and we wouldn't be here!
  3. 5. This gas is the most abundant element in the universe
  4. 6. I am a halogen, and I purify the water in swimming pools.
  5. 7. I am a noble gas, and like Krypton, I'm used for flashlights, but I'm also used in car headlamps and high density lamps.
  6. 11. I am a noble gas, and all of my isotopes are radioactive.