What type of change produced the rust shown above? a. chemical, because a new substance with new properties was formed b. physical, because a new substance with new properties was formed c. physical, because the chemical makeup of the metal did not change d. chemical, because the chemical makeup of the metal did not change

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.