Where did the water on earth come from? a. mainly volcanic eruptions b. probably from a combination of sources c. probably from the nebula that formed the planet d. mainly comets and asteroids ! science!

I think the answer to this is C but it could also be D. There are theories out that that water came from comets and asteroids or nebula that formed the planet. 

1) clean up you lab area2) dispose of the chemicals as instructed by your teacher3) put everything back where it belongs unless your teacher tells you otherwise4) dispose of gloves5) wash hands with soap and water

Iwould say overuse ( but not 100% sure ) in the u.s. we tend to overuse water by leaving it running, throwing it away, taking long showers, etc.