Please help me with this homework

If 22.5 liters of oxygen reacted with excess of hydrogen, how many liters of water vapor could be produced?

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.

Write a hypothesis that answers the lesson question, “while observing a chemical reaction, how can you tell which reactant is limiting? ” hypothesis: if a substance is the limiting reactant, then . . because . .