Assertion :- In an isolated system the entropy increases due to spontanous process.
Reason :- The processes in an isolated system are adiabatic.

Options

A. If both Assertion & Reason are True & the Reason is a correct explanation of the Assertion.
B. If both Assertion & Reason are True but Reason is not a correct explanation of the Assertion.
C. If Assertion is True but the Reason is False.
D. If both Assertion & Reason are false.

Answer

To analyze the given statements, we will break down the assertion and reason step by step.

### Step 1: Understanding the Assertion
The assertion states that "In an isolated system, the entropy increases due to spontaneous processes."

**Explanation:**
- According to the second law of thermodynamics, in an isolated system, the total entropy can never decrease; it either increases or remains constant. Spontaneous processes are those that occur without external intervention, and they tend to increase the entropy of the system.

### Step 2: Understanding the Reason
The reason states that "The processes in an isolated system are adiabatic."

**Explanation:**
- An adiabatic process is one in which there is no heat exchange between the system and its surroundings. In an isolated system, not only is there no heat exchange, but there is also no exchange of work or matter with the surroundings. Thus, all processes occurring in an isolated system are indeed adiabatic.

### Step 3: Evaluating the Relationship Between Assertion and Reason
Now we need to determine if the reason provided is a correct explanation for the assertion.

**Analysis:**
- While both statements are true, the reason does not explain why the entropy increases in an isolated system. The increase in entropy is a consequence of the second law of thermodynamics, not merely because the processes are adiabatic. The reason describes a characteristic of isolated systems but does not elucidate the cause of entropy increase.

### Conclusion
Thus, we can conclude that:
- The assertion is true.
- The reason is true.
- However, the reason is not the correct explanation for the assertion.

Therefore, the final answer is that both the assertion and reason are true, but the reason is not the correct explanation for the assertion.

### Final Answer:
Both assertion and reason are true, but the reason is not the correct explanation of the assertion.

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