Which of the following statements is true? a. protons are located outside the nucleus of an atom. b. the nucleus of an atom contains protons and neutrons. c. electrons do not have mass. d. individual atoms can be seen with the naked eye.

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.