At 300K, a sample of methane exhibits Z=0.92 at 5.0atm and Z=1.04 at 80atm. Which of the following best explains why Z is less than 1 at 5.0atm?
a) The finite volume of the methane molecules occupies a significant fraction of the container volume, decreasing the free volume.
b) High kinetic energy at 300K leads to more frequent, forceful collisions that increase the measured pressure relative to an ideal gas.
c) Intermolecular attractions reduce the measured pressure relative to an ideal gas.
d) Random experimental error has led to an overestimation of the amount of gas present, making Z appear smaller than 1.