28 g each of the following gases are taken at `27^(@C` and 600 mm pressures. Which of these will have least volume ?

Options

A. HBr
B. HCl
C. HF
D. HI

Explanation

To determine which gas will have the least volume when 28 g of each is taken at 27°C and 600 mm pressure, we can use the ideal gas law and the relationship between mass, molar mass, and volume.

### Step-by-Step Solution:

1. **Understand the Relationship**: The volume of a gas is directly proportional to the number of moles of the gas. The number of moles (n) can be calculated using the formula:
\[ n = \frac{\text{mass}}{\text{molar mass}} \]
Therefore, volume (V) can be expressed as:
\[ V \propto n \propto \frac{\text{mass}}{\text{molar mass}} \]

2. **Given Data**: We have:
- Mass of each gas = 28 g
- Temperature = 27°C (which is 300 K)
- Pressure = 600 mm Hg

3. **Calculate Molar Mass**: Since the mass is constant (28 g), the volume will depend on the molar mass of each gas. The gas with the highest molar mass will have the least number of moles, and thus the least volume.

4. **Identify Molar Masses**: List the molar masses of the gases provided in the question. For example:
- Hydrogen iodide (HI): Molar mass = 127 g/mol
- Other gases (for example, O2, N2, CO2, etc.) will have different molar masses.

5. **Compare Molar Masses**: Identify which gas has the highest molar mass. The gas with the highest molar mass will yield the least volume when 28 g is used.

6. **Conclusion**: Based on the molar masses, the gas with the highest molar mass (in this case, HI) will have the least volume.

### Final Answer:
The gas with the least volume is Hydrogen iodide (HI).