2. the water on earth came from ancient a. Volcanic activity
b. Collisions with comets that contained ice
c. Both answers a and b
d. None of the above

3. How much of the earth’s water is held in the oceans?
a. 25%
b. 50%
c. 75%
d. Almost 100%

4. Which of the following is a solvent?
a. Rocks
b. Water
c. Ice
d. Steam

5. Water enters the ocean from
a. Rivers that empty into the ocean
b. Rain
c. Groundwater
d. All of the above

6. The major component of salt water is
a. Water
b. Salt
c. Other minerals
d. None of the above