Which is true about different forms of hydrogen :

Options

A. ortho hydrogen has same spins of two nuclei clockwise or anticlockwise
B. para hydrogen has different spins of two nuclei
C. at absolute zero, there is `100%` para form and at high temperature, there is `75%` ortho form
D. all are correct.

Explanation

To determine which statements about the different forms of hydrogen are true, we need to analyze the properties of ortho and para hydrogen.

### Step-by-Step Solution:

1. **Understanding the Forms of Hydrogen**:
- Dihydrogen (H₂) exists in two forms: ortho and para hydrogen. These are known as nuclear spin isomers.

2. **Defining Ortho and Para Hydrogen**:
- **Ortho Hydrogen**: In this form, the spins of the two hydrogen nuclei (protons) are aligned in the same direction (both clockwise or both anticlockwise). This means they have a net spin of 1.
- **Para Hydrogen**: In this form, the spins of the two hydrogen nuclei are opposite (one clockwise and one anticlockwise). This results in a net spin of 0.

3. **Stability of the Forms**:
- Para hydrogen is more stable than ortho hydrogen because the opposing spins cancel each other out, leading to a lower energy state.

4. **Behavior at Absolute Zero**:
- At absolute zero (0 Kelvin), only para hydrogen exists. This is because thermal energy is insufficient to maintain the ortho form.

5. **Analyzing the Statements**:
- **Statement 1**: "Ortho hydrogen has the same spins of nuclei (clockwise or anticlockwise)."
- This is **true**.
- **Statement 2**: "Para hydrogen has different spins of two nuclei."
- This is **true**.
- **Statement 3**: "At absolute zero, there is 100% para form."
- This is **true**.
- **Statement 4**: "At high temperature, there is 75% ortho form."
- This is **false**. The distribution of ortho and para forms does not depend on temperature in a straightforward manner; rather, it is a function of the equilibrium between the two forms.

### Conclusion:
- The true statements about different forms of hydrogen are:
- Statement 1: True
- Statement 2: True
- Statement 3: True
- Statement 4: False

### Final Answer:
Statements 1, 2, and 3 are true, while statement 4 is false.

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