According to the Kinetic Theory, what does NOT occur when the temperature of a constant volume of gas is increased?

Analyze the question: We are asked which effect does NOT happen when a gas at constant volume is heated, according to the Kinetic Theory.

Concept: Temperature is a measure of the average kinetic energy of gas molecules. Mean KE = (3/2)kT, so raising T raises the mean KE and the mean (r.m.s.) speed of the molecules.

Step by step, checking each option when T increases at constant V:

• A. Decrease in the mean kinetic energy: Mean KE is proportional to T, so it increases. A decrease does NOT occur. ✔ (this is the answer)
• B. Increase in mean speed: Faster molecules, since KE = ½mv². This DOES occur.
• C. Increase in momentum change at each collision: Molecules hit the walls with greater speed, so the change in momentum (2mv) is larger. This DOES occur.
• D. Increase in number of collisions per second: Faster molecules travel the container more quickly, so they hit the walls more often. This DOES occur.
• E. Increase in pressure: From P = (1/3)ρ<c²>, or Pressure Law (P ∝ T at constant volume), pressure rises. This DOES occur.

Answer: The only statement that does not occur is the decrease in mean kinetic energy, so the answer is A.

Tip: In "which does NOT occur" questions, look for the option that contradicts the basic relationship. Here, temperature up means KE up, speed up, collisions up, and pressure up. Anything saying "decrease" is the odd one out.