Where is most of the dark matter in our galaxy thought to exist?

Which are evidence of the seafloor spreading? a. molten material b. magnetic stripes c. continental material d. drilled core samples e. ocean water samples

The ozone hole is at its biggest each year in the ? hemisphere in the ? season.

Ozone in the upper atmosphere has been depleted by a. sulfur dioxide. b. chlorofluorocarbons. c. carbon dioxide. d. oxygen.