| Answer | Crossword Clue |
|---|---|
| ARGON | Roughly 1% of the atmosphere |
| ARGON | Roughly 1% of the earth's atmosphere |
| ARGON | About 1% of the atmosphere |
| ARGON | Almost 1% of the Earth's atmosphere |
| ARGON | About 1% of the Earth's atmosphere |
| OXYGEN | Roughly 21% of the atmosphere |
