Assertion : In a nuclear process energy is released if total binding energy of daughter nuclei is more than the total binding energy of parent nuclei.
Reason: If energy is released then total mass of daughter nuclei is less than the total mass of parent nuclei.

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 are true but Reason is not correct explanation of Assertion.
C. If Assertion is true but Reason is false.
D. If Assertion is false but Reason is true.

Answer

To solve the problem, we need to analyze the assertion and reason given in the question step by step.

### Step 1: Understanding the Assertion
The assertion states that "In a nuclear process, energy is released if the total binding energy of daughter nuclei is more than the total binding energy of parent nuclei."

**Explanation**:
- The binding energy of a nucleus is the energy required to disassemble it into its constituent protons and neutrons.
- If the binding energy of the daughter nuclei is greater than that of the parent nuclei, it implies that the daughter nuclei are more stable than the parent nuclei.
- When a nuclear reaction occurs and the daughter nuclei have a higher binding energy, energy is released in the process.

### Step 2: Understanding the Reason
The reason states that "If energy is released, then the total mass of daughter nuclei is less than the total mass of parent nuclei."

**Explanation**:
- According to Einstein's mass-energy equivalence principle (E=mc²), energy and mass are interchangeable.
- When energy is released in a nuclear reaction, it corresponds to a decrease in mass, known as the mass defect.
- Therefore, if energy is released, it implies that the mass of the daughter nuclei must be less than that of the parent nuclei.

### Step 3: Analyzing the Relationship
Now, we need to analyze the relationship between binding energy and mass:
- The binding energy (BE) can be expressed in terms of mass defect (Δm) as follows:
\[ BE = Δm \cdot c^2 \]
- If the binding energy of the daughter nuclei is greater than that of the parent nuclei, we can express this as:
\[ BE_{daughter} > BE_{parent} \]
- This can be rewritten using mass defect:
\[ Δm_{daughter} \cdot c^2 > Δm_{parent} \cdot c^2 \]
- Since c² is a constant and positive, we can simplify this to:
\[ Δm_{daughter} > Δm_{parent} \]
- This implies that the mass of the daughter nuclei is less than the mass of the parent nuclei, confirming the reason.

### Conclusion
Both the assertion and the reason are correct, and the reason correctly explains why the assertion is true. Therefore, the correct answer is that both the assertion and reason are true, and the reason is valid.

### Final Answer
The correct option is A: Both the assertion and reason are true, and the reason is a correct explanation of the assertion.

---