Question

In an isothermal expansion of an ideal gas, the internal energy of the gas:

• A. Increases as the temperature increases.
• B. Decreases because the temperature decreases.
• C. Remains constant.
• D. Increases and then decreases during the expansion.

Hint:

For an ideal gas undergoing an isothermal process, remember that its internal energy is only a function of temperature. Since temperature remains constant, internal energy remains unchanged.

Answer 1

The Correct Option is C

In an isothermal process, the temperature of the system remains constant. Since the internal energy of an ideal gas depends only on temperature (according to the first law of thermodynamics), if the temperature is constant, the internal energy also remains constant. In the case of isothermal expansion, the gas does work on the surroundings, but this energy is provided by the heat absorbed from the surroundings, so the internal energy does not change. Therefore, the correct answer is option (C).