Which of the following most likely happens during a physical change? a) New atoms are introduced in the molecules of the substance.

b)A substance reacts differently with a chemical before and after the change.

c)An irreversible process takes place.

d)Substance changes its form but not its molecular composition.

its science-

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.