Which of the following is NOT a factor affecting the diffusion of gases?

• A. Surface area available
• B. Temperature of the gas
• C. Partial pressure gradient
• D. Membrane thickness

Answer: (B)

The correct choice indicates an aspect that does not influence the diffusion of gases. While surface area available, partial pressure gradient, and membrane thickness are all critical factors affecting the rate of gas diffusion, the temperature of the gas is not typically considered one of these direct factors in a traditional sense.

To clarify, gas diffusion occurs based on established principles outlined by Fick's laws, which specifically reference surface area, concentration (or partial pressure) gradients, and the thickness of membranes as direct influencers of the diffusion rate. A greater surface area allows more gas to diffuse at once, a steeper partial pressure gradient drives more diffusion, and a thinner membrane allows gases to pass through more easily.

Although temperature can influence the kinetic energy of gas molecules and therefore indirectly affect diffusion in terms of molecular speed, it is not a characteristic of diffusion itself in the context of the factors listed. Thus, recognizing that temperature does not function as a primary determinant makes this choice valid in the discussion of gas diffusion mechanisms.