1. D. It is the part of Earth that contains living organisms.
2. D. a volcano eruption
3. B. It allows life to exist.
4. A. 24
5. D. Earth's period of rotation is shorter; Earth's period of revolution is longer.
6. A. It pulls the moon toward Earth.
7. A. because Earth rotates to the east
8. B. As Earth rotates toward the east, the sun appears to rise in the east and set in the west.
And here's a bonus joke for you:
Why did the scarecrow win an award?
Because he was outstanding in his field!