The solubility of a specific non-volatile salt is 4 g in 100 g of water at `25^(@)C`. If `2.0 g, 4.0 g and 6.0 g` of the salt added of 100 g of water at `25^(@)`, in system` X, Y and Z`. The vapour pressure would be in the order:

Options

A. `X lt Y lt Z`
B. `X gtY gtZ`
C. `Z gtX =Y`
D. `X gt Y = Z`

Answer

To determine the order of vapor pressure for the systems X, Y, and Z based on the solubility of a non-volatile salt in water, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the solubility of the salt**:
The solubility of the salt is given as 4 g in 100 g of water at 25°C. This means that at this temperature, a maximum of 4 g of salt can dissolve in 100 g of water to form a saturated solution.

2. **Analyze the amounts of salt added**:
- In system X: 2.0 g of salt is added.
- In system Y: 4.0 g of salt is added.
- In system Z: 6.0 g of salt is added.

3. **Determine the saturation of each system**:
- **System X**: 2.0 g of salt is less than the solubility limit (4 g). Therefore, it will dissolve completely and the solution will be unsaturated.
- **System Y**: 4.0 g of salt is equal to the solubility limit. Therefore, it will dissolve completely and the solution will be saturated.
- **System Z**: 6.0 g of salt exceeds the solubility limit. Only 4 g will dissolve, and the solution will also be saturated.

4. **Understand the relationship between vapor pressure and concentration**:
The vapor pressure of a solution is inversely related to the concentration of the solute. The more solute present (up to the saturation point), the lower the vapor pressure. Conversely, a lower concentration of solute results in a higher vapor pressure.

5. **Compare the vapor pressures**:
- **System X** (2.0 g of salt): This system has the lowest concentration of solute, leading to the highest vapor pressure.
- **System Y** (4.0 g of salt): This system is saturated, leading to a lower vapor pressure than system X.
- **System Z** (6.0 g of salt): Although it is also saturated, it has the same concentration of solute as system Y (4 g), leading to the same vapor pressure as system Y.

6. **Order the vapor pressures**:
Based on the analysis:
- Vapor pressure of X > Vapor pressure of Y = Vapor pressure of Z

### Conclusion:
The order of vapor pressure for the systems X, Y, and Z is:
**X > Y = Z**