Final answer:
The false statement regarding the rate of diffusion is that larger molecules move faster and that greater distance speeds up the diffusion. In fact, larger molecules move slower, and greater distance slows down diffusion.
Step-by-step explanation:
The student's question pertains to the factors affecting the rate of diffusion of a gas. The correct statements are that the rate of diffusion is directly proportional to the concentration gradient and available cross-sectional area, inversely proportional to the square root of the gas's molecular weight according to Graham's Law, and directly proportional to temperature.
Regarding the provided options:
a. The rate of diffusion is directly proportional to the concentration gradient.
b. The rate of diffusion is directly proportional to the available cross-sectional area.
c. The rate of diffusion is inversely proportional to the square root of the gas's molar mass (GMW or molecular weight).
d. The rate of diffusion is directly proportional to temperature, as increased temperature increases the kinetic energy of the molecules, thus increasing diffusion.
Therefore, the false statement regarding the rate of diffusion of a gas is: Larger molecules move slower than lighter molecules. Greater distance speeds up the diffusion. This statement is incorrect because larger molecules actually move slower, and greater distance does not speed up diffusion but rather slows it down.