Avogadro's law relates the volume of a gas to the number of moles of gas when temperature and pressure are constant. according to this law, how would the volume of a gas change if a reaction produced 1 mole of gas from 2 moles of gaseous reactants? a. the volume would be one-fourth of the original volume. b. the volume would be four times the original volume. c. the volume would be two times the original volume. d. the volume would be one-half of the original volume.