Which is distilled first ?

Options

A. Liquid `H_(2)`
B. Liquid `CO_(2)`
C. Liquid `O_(2)`
D. Liquid `N_(2)`

Answer

To determine which substance is distilled first among liquid H2, liquid CO2, liquid O2, and liquid N2, we need to analyze their molecular masses and boiling points. The substance with the lowest molecular mass will generally have the weakest intermolecular forces and therefore the lowest boiling point, leading it to be distilled first.

### Step-by-Step Solution:

1. **Identify the Substances**: The substances we need to consider are:
- Liquid H2 (Hydrogen)
- Liquid CO2 (Carbon Dioxide)
- Liquid O2 (Oxygen)
- Liquid N2 (Nitrogen)

2. **Calculate Molecular Masses**:
- For **H2**:
\[ \text{Molecular mass} = 2 \times 1 = 2 \text{ g/mol} \]
- For **CO2**:
\[ \text{Molecular mass} = 12 \text{ (C)} + 2 \times 16 \text{ (O)} = 12 + 32 = 44 \text{ g/mol} \]
- For **O2**:
\[ \text{Molecular mass} = 2 \times 16 = 32 \text{ g/mol} \]
- For **N2**:
\[ \text{Molecular mass} = 2 \times 14 = 28 \text{ g/mol} \]

3. **Compare Molecular Masses**:
- H2: 2 g/mol
- CO2: 44 g/mol
- O2: 32 g/mol
- N2: 28 g/mol

4. **Determine the Substance with the Lowest Molecular Mass**:
- The molecular mass of H2 (2 g/mol) is the lowest among all the substances listed.

5. **Conclusion**:
- Since H2 has the lowest molecular mass, it will have the weakest intermolecular forces, leading to the lowest boiling point. Therefore, liquid H2 will be distilled first.

### Final Answer:
**Liquid H2 (Option A) is distilled first.**