Question

In which of the following processes the internal energy of system remain constant?

• A. Isobaric Process
• B. Isochoric Process
• C. Isothermal Process
• D. Adiabatic Process

Hint:

Internal energy of an ideal gas depends only on temperature.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
For an ideal gas, internal energy \(U\) depends only on temperature. So \(U\) stays constant only when the temperature stays constant.

Step 2: Check each process:
Isobaric process: pressure is constant but the volume and temperature change, so \(U\) changes. This is wrong.
Isochoric process: volume is constant, so no work is done, but heat added raises the temperature and \(\Delta U = q_V \neq 0\). This is wrong.
Isothermal process: temperature is constant, so \(\Delta T = 0\) and \(\Delta U = 0\). This is correct, and the heat absorbed equals the work done by the gas.
Adiabatic process: \(q = 0\), but \(\Delta U = w \neq 0\), so the temperature changes. This is wrong.

Final Answer:
Only the isothermal process keeps the internal energy constant, which is option (C). \[ \boxed{\text{Isothermal process}} \]