Which is distilled first ?

Options

A. liquid `H _(2)`
B. `NHO_(3)`
C. `H_(2) SO_(3)`
D. `HNO_(2)`

Explanation

To determine which substance distills first among the given options (liquid hydrogen, HNO3, H2SO3, and HNO2), we need to analyze their boiling points. The substance with the lowest boiling point will distill first.

### Step-by-Step Solution:

1. **Understand Distillation**: Distillation is a process that separates components based on their boiling points. The component with the lowest boiling point will vaporize first and can be collected as a distillate.

2. **Identify the Given Substances**: The substances to consider are:
- Liquid Hydrogen (H2)
- Nitric Acid (HNO3)
- Sulfurous Acid (H2SO3)
- Nitrous Acid (HNO2)

3. **Determine Boiling Points**: We need to find the boiling points of each of these substances:
- **Liquid Hydrogen (H2)**: Boiling point = -252.87 °C
- **Nitric Acid (HNO3)**: Boiling point = 83 °C
- **Sulfurous Acid (H2SO3)**: Boiling point = 34.6 °C
- **Nitrous Acid (HNO2)**: Boiling point = 23.7 °C

4. **Compare Boiling Points**: Now, we compare the boiling points:
- H2: -252.87 °C
- HNO3: 83 °C
- H2SO3: 34.6 °C
- HNO2: 23.7 °C

5. **Identify the Lowest Boiling Point**: From the comparison, we see that liquid hydrogen (H2) has the lowest boiling point at -252.87 °C.

6. **Conclusion**: Since liquid hydrogen has the lowest boiling point, it will distill first.

### Final Answer:
**Liquid Hydrogen (H2) distills first.**

---