In a sample of an ideal gas, the average translational kinetic energy of a molecule is 5.0 × 10^-21 J. If the number of molecules in the sample is doubled while the temperature remains constant, what is the new average translational kinetic energy of a molecule?
Show the answer and explanation
Correct answer
B. 5.0 × 10^-21 J
Principle or equation
The average translational kinetic energy of a molecule in an ideal gas depends only on the absolute temperature: KE_avg = (3/2)kT. It is independent of the number of molecules.
Why this answer is correct
Since the temperature is constant, the average translational kinetic energy per molecule remains the same, 5.0 × 10^-21 J.
Example
If the average kinetic energy is 6.0×10^-21 J at 300 K, it remains 6.0×10^-21 J at the same temperature even if the number of molecules changes.
This published item includes a stored explanation and passed the platform’s publication workflow. It is independent preparation material, not a claim of an official or recalled examination question.