| Answer | Crossword Clue |
|---|---|
| NITROGEN | Four-fifths of the earth's atmosphere. |
| NITROGEN | Four-fifths of the atmosphere |
| ARGON | .93% of the earth's atmosphere |
| ARGON | Almost 1% of the Earth's atmosphere |
| ARGON | About 1% of the Earth's atmosphere |
| NITROGEN | Almost 80% of the Earth's atmosphere |
| ARGON | Roughly 1% of the earth's atmosphere |
| ARGON | About 1 percent of the Earth's atmosphere |
| SEAWEED | Major source of oxygen in the earth's atmosphere |
