Question

Which of the following statements about Earth's atmosphere is true?

Answer choices:
1.Earth's atmosphere contains 78 percent water vapor, which is essential to life.
2. Earth's atmosphere contains 21 percent oxygen.
3. Earth's atmosphere contains carbon dioxide, which all life forms require.
4. Earth's atmosphere allows radiation from the sun to pass through it and warm Earth's surface.

Answer 1

4. Earth's atmosphere allows radiation from the sun to pass through it and warm Earth's surface.

Answer 2

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