Question

In thermodynamics, for an isochoric process, which one of the following statement is INCORRECT?

• A. Energy exchanged is used to do work and also to change internal energy.
• B. It is a constant volume process.
• C. No work is done in the process.
• D. Temperature of the system changes during the process.

Hint:

Always read the question stem carefully for words like INCORRECT or NOT. It's easy to look at option (B) or (C), recognize them as true facts about an isochoric process, and select them mistakenly without reading the entire question!
center Isochoric $\implies \Delta V = 0 \implies W = 0 \implies Q = \Delta U$ center

Answer 1

The Correct Option is A

Step 1: Understanding the Question:
The question asks us to identify the

INCORRECT statement regarding an

isochoric thermodynamic process from the options provided.

Step 2: Key Formula or Approach:
An isochoric process is defined as a thermodynamic process in which the volume of the system remains completely constant ($V = \text{constant} \implies \Delta V = 0$).
The work done ($W$) by a gas during a thermodynamic transformation is given by the integral: $$W = \int P \, dV$$ Since the volume is constant ($\Delta V = 0$), the work done is exactly zero ($W = 0$).
According to the First Law of Thermodynamics: $$Q = \Delta U + W$$ Substituting $W = 0$ simplifies the expression to $Q = \Delta U$, meaning all added heat energy goes directly into changing the internal energy (and thus changing the temperature), rather than doing mechanical work.

Step 3: Detailed Explanation:
Let's evaluate each option to find the incorrect statement:

Option (B) & (C): These accurately state that the volume is constant and no work is done ($W = 0$). Therefore, these statements are correct.

Option (D): Adding heat to a fixed volume increases its internal energy ($\Delta U = nC_v\Delta T$), which changes the system's temperature. This statement is correct.

Option (A): This statement claims that the added energy is split to perform work and alter internal energy. Since work done is strictly zero ($W = 0$) in an isochoric process, this statement is false.
Since the question asks for the

incorrect statement, option (A) is our target choice.

Step 4: Final Answer:
The incorrect statement is option (A).