Assertion : Ortho and Para dihydrogen are nuclear spin isomers.
Reason : They have same nuclear spins.

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 solve the question, we need to analyze the assertion and the reason provided.

**Assertion:** Ortho and para dihydrogen are nuclear spin isomers.

**Reason:** They have the same nuclear spins.

### Step-by-Step Solution:

1. **Understanding Ortho and Para Dihydrogen:**
- Dihydrogen (H₂) can exist in two forms based on the spins of its two protons: ortho and para.
- In ortho hydrogen, both protons have their spins aligned parallel to each other. This configuration has a total nuclear spin of 1.
- In para hydrogen, the spins of the two protons are aligned anti-parallel (opposite to each other), resulting in a total nuclear spin of 0.

2. **Identifying Nuclear Spin Isomers:**
- Nuclear spin isomers are defined as different arrangements of nuclear spins in a molecule that result in different energy states.
- Since ortho and para hydrogen have different arrangements of proton spins, they are indeed nuclear spin isomers.

3. **Evaluating the Reason:**
- The reason states that ortho and para dihydrogen have the same nuclear spins. This is incorrect because ortho hydrogen has a total nuclear spin of 1, while para hydrogen has a total nuclear spin of 0. Thus, they do not have the same nuclear spins.

4. **Conclusion:**
- The assertion is true: ortho and para dihydrogen are nuclear spin isomers.
- The reason is false: they do not have the same nuclear spins.
- Therefore, the correct answer is that the assertion is true but the reason is false.

### Final Answer:
The correct answer is option C: Assertion is true but reason is false.

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