Answer: A
Explanation:
Oxygen makes up another 20 to 21 percent of our atmosphere. It's essential for life on Earth, and interestingly enough, it is poisonous when highly concentrated. Our concentration of 20 to 21 percent seems just right.
Answer:
c: Carbon Dioxide
Step-by-step explanation:
Earth's atmosphere is mainly made up of:
78% nitrogen
21% oxygen
0.03% carbon dioxide
And smaller percentages of other elements. Therefore, out of the options, the answer is carbon dioxide
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