Question

Which of the following statements is NOT CORRECT?
In an isothermal process,
a. there is perfect thermal equilibrium with environment.
b. there is no change in internal energy during the process.
c. the work done is equal to zero.
d. the time taken is very large.

• A. c
• B. a
• C. d
• D. b

Hint:

In an isothermal process the temperature is constant but heat is exchanged and work is done, so work is not zero.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept
Check each statement one by one against the properties of an isothermal process.

Step 2: Calculation
a is true (thermal equilibrium), b is true ($\Delta U=0$), d is true (very slow process). c is false because $W=nRT\ln\frac{V_{2}}{V_{1}}\neq 0$.

Step 3: Why the other options fail
The other options are correct statements, so they cannot be the answer to a question that asks for the incorrect one.

Final Answer:
Statement c is the incorrect one. \[ \boxed{\text{(A) }\text{c}} \]