When an ideal gas is cooled at constant volume until the pressure becomes half of the originalpressure, then the average translational kinetic energy of the gas molecules
Correct answer: B. Becomes half the original.
- A. Remains unchanged.
- B. Becomes half the original.
- C. Becomes twice the original.
- D. Becomes thrice the original.
Explanation
In an ideal gas, the average translational kinetic energy of the molecules is directly proportional to the absolute temperature of the gas. According to the ideal gas law, PV = nRT, where P is pressure, V is volume, T is temperature, and n and R are constants for a given amount of gas. When the gas is cooled at constant volume and the pressure is reduced to half its original value, the temperature must also be reduced to half (since V is constant and nR is constant). Therefore, the average translational kinetic energy, which depends on temperature, also becomes half of its original value. Option B reflects this understanding correctly, while Options A, C, and D do not align with the principles of the ideal gas law.
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