Correct among the following is/are

Options

A. Ortho hydrogen is thermodynamically more stable
B. Parahydrogen is kinetically more stable
C. At room temperature para hydrogn is major component
D. Ortho and para hydrogens always present in 50:50 ratio

Answer

To solve the question regarding the stability and ratios of ortho and para hydrogen, let's analyze each statement step by step.

### Step 1: Understand the Definitions
- **Ortho Hydrogen**: This form of hydrogen has the spins of both hydrogen nuclei in the same direction.
- **Para Hydrogen**: This form has the spins of the hydrogen nuclei in opposite directions.

### Step 2: Analyze Stability
- **Thermodynamic Stability**: At lower temperatures (0 Kelvin), para hydrogen is more stable. However, as the temperature increases, ortho hydrogen becomes more thermodynamically stable.
- **Kinetic Stability**: Para hydrogen is kinetically more stable at lower temperatures because it has a lower energy state compared to ortho hydrogen.

### Step 3: Examine the Statements
1. **Ortho hydrogen is thermodynamically more stable**: This is **true** at higher temperatures.
2. **Para hydrogen is kinetically more stable**: This is also **true** at lower temperatures.
3. **At room temperature, para hydrogen is the major component**: This is **false**; at room temperature, ortho hydrogen is the major component with a ratio of approximately 3:1.
4. **Ortho and para hydrogen are always present in a 50-50 ratio**: This is **false**; the ratio changes with temperature, being 1:1 at liquefaction temperature and approximately 3:1 at room temperature.

### Conclusion
- The correct statements are:
- Ortho hydrogen is thermodynamically more stable (True).
- Para hydrogen is kinetically more stable (True).
- The incorrect statements are:
- At room temperature, para hydrogen is the major component (False).
- Ortho and para hydrogen are always present in a 50-50 ratio (False).

### Final Answer
The correct statements are:
1. Ortho hydrogen is thermodynamically more stable.
2. Para hydrogen is kinetically more stable.