Assertion Molar heat capacity cannot be defined for isothermal process.
Reason In isothermal prcess p-V versus T graph is a dot.

Options

A. Both assertion and reson are true and reason is the correct explanation of assertion
B. Both assetion and reason are true but reason is not the correct explanation of assertion
C. Assertion is true but reason is false
D. Both assetion and reason are flase

Answer

To solve the given assertion and reason question, we will analyze both statements step by step.

### Step 1: Understand the Assertion
The assertion states that "Molar heat capacity cannot be defined for isothermal process."

- **Molar Heat Capacity**: This is defined as the amount of heat required to change the temperature of one mole of a substance by one degree Celsius (or one Kelvin).
- **Isothermal Process**: In this process, the temperature of the system remains constant throughout the process.

Since molar heat capacity requires a change in temperature to be defined, and in an isothermal process, the temperature does not change, we can conclude that the assertion is correct.

### Step 2: Understand the Reason
The reason states that "In isothermal process, the p-V versus T graph is a dot."

- **p-V vs. T Graph**: In an isothermal process for an ideal gas, the product of pressure (P) and volume (V) remains constant (PV = nRT, where n is the number of moles and R is the gas constant).
- Since the temperature (T) is constant, the graph of pressure-volume (P-V) versus temperature (T) will not show a range of values but rather a single point (dot) at that constant temperature.

Thus, the reason is also correct.

### Step 3: Analyze the Relationship Between Assertion and Reason
While both the assertion and the reason are correct, the reason does not provide a correct explanation for the assertion. The assertion is about the definition of molar heat capacity, while the reason discusses the nature of the P-V vs. T graph in an isothermal process.

### Conclusion
Both the assertion and reason are true, but the reason is not the correct explanation of the assertion. Therefore, the answer is:

**Both assertion and reason are true, but reason is not the correct explanation of assertion.**

### Final Answer
The correct option is: **B** (Both assertion and reason are true, but reason is not the correct explanation of assertion).

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