Assertion : An exothermic process which is non-spontaneous at high temperature may become spontaneous at low temperature.
Reason : Spontaneous process is an irreversible process and may be reversed by some external agency.

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion.
B. If both assertion and reason are true but reason is not the correct explanation of assertion
C. If assertion is true but reason is false.
D. If both assertion and reason are false.

Explanation

To solve the assertion and reason question, we need to analyze both statements carefully.

### Step 1: Understand the Assertion
The assertion states that "An exothermic process which is non-spontaneous at high temperature may become spontaneous at low temperature."

- **Exothermic Process**: This means that the change in enthalpy (ΔH) is negative.
- **Non-Spontaneous at High Temperature**: For a process to be non-spontaneous, the Gibbs free energy change (ΔG) must be positive. The relationship is given by the equation:

\[ \Delta G = \Delta H - T\Delta S \]

Here, if ΔH is negative (exothermic) and ΔG is positive at high temperature, it implies that the term \(T\Delta S\) is larger than ΔH (which is negative).

### Step 2: Analyze the Conditions for Spontaneity
At low temperatures, the influence of the \(T\Delta S\) term decreases. If ΔS is negative, then at low temperatures, \(T\Delta S\) could be small enough that ΔG becomes negative, making the process spontaneous.

### Step 3: Conclusion on the Assertion
Thus, the assertion is correct: an exothermic process that is non-spontaneous at high temperatures may become spontaneous at low temperatures.

### Step 4: Understand the Reason
The reason states that "Spontaneous process is an irreversible process and may be reversed by some external agency."

- **Spontaneous Process**: This is indeed generally considered irreversible under normal conditions. However, it can be reversed by applying external energy.
- The statement is correct, but it does not directly explain the assertion regarding temperature effects on spontaneity.

### Step 5: Conclusion on the Reason
The reason is also correct, but it does not provide a valid explanation for why the assertion is true.

### Final Conclusion
Both the assertion and the reason are correct, but the reason is not the correct explanation for the assertion. Therefore, the correct answer is that both statements are true, but the reason does not explain the assertion.

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

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