Step 1: Understanding the Concept:
An isothermal process is a thermodynamic process in which the temperature of the system remains constant throughout (\(\Delta T = 0\)).
The internal energy of an ideal gas depends only on its absolute temperature. Step 2: Key Formula or Approach:
First Law of Thermodynamics: \(Q = \Delta U + W\).
For ideal gas: \(\Delta U = n C_V \Delta T\). Step 3: Detailed Explanation:
In an isothermal process, \(\Delta T = 0\), which implies \(\Delta U = 0\).
The internal energy does not change, so options (C) and (B) are incorrect.
Substituting \(\Delta U = 0\) into the First Law:
\[ Q = 0 + W \implies Q = W \]
This means all the heat supplied to the gas is converted entirely into external work done by the gas during expansion.
Thus, there will be external work done. Option (D) is incorrect because there is no rise in temperature. Step 4: Final Answer:
When heat is given in an isothermal process, it results in external work done.