21. Which of the following entities has the greatest mass?
a. One atom of aluminum
b. One molecule of fluorine
c. One atom of phosphorus
d. One molecule of methane

This classification of drug typically changes the brain's chemistry and reduces its ability to create its own endorphins.

What happens to isotopes that are unstable?

What effect would average population growth have on land usage? a. urban use of land would rise to more than 30 percent of available land. b. industrial use of land would rise to more than 30 percent of available land. c. the percentage of available land used as cropland would stay the same. d. cropland would fall to about 10 percent of available land.