In the following aqueous solutions
(A) `1m` surcose (B) `1m` potassium ferricyanide (C) `1m` potassium sulphate
maximum value of vapour pressure of solution is that of:

Options

A. A
B. B
C. C
D. equal

Answer

To determine which of the given solutions has the maximum vapor pressure, we need to analyze the van’t Hoff factor (i) for each solute. The van’t Hoff factor indicates the number of particles the solute dissociates into when dissolved in a solvent. The greater the number of particles, the greater the lowering of vapor pressure, and consequently, the lower the vapor pressure of the solution.

### Step-by-Step Solution:

1. **Identify the Solutes:**
- (A) Sucrose
- (B) Potassium ferricyanide (K₃[Fe(CN)₆])
- (C) Potassium sulfate (K₂SO₄)

2. **Determine the van’t Hoff Factor (i) for Each Solute:**
- **Sucrose (C₁₂H₂₂O₁₁):**
- Sucrose is a non-electrolyte and does not dissociate in solution.
- Therefore, \( i = 1 \).

- **Potassium Ferricyanide (K₃[Fe(CN)₆]):**
- When potassium ferricyanide dissociates, it produces:
\[ K₃[Fe(CN)₆] \rightarrow 3K^+ + [Fe(CN)₆]^{3-} \]
- This results in a total of 4 particles.
- Therefore, \( i = 4 \).

- **Potassium Sulfate (K₂SO₄):**
- When potassium sulfate dissociates, it produces:
\[ K₂SO₄ \rightarrow 2K^+ + SO₄^{2-} \]
- This results in a total of 3 particles.
- Therefore, \( i = 3 \).

3. **Analyze the Relative Lowering of Vapor Pressure:**
- The relative lowering of vapor pressure is directly proportional to the van’t Hoff factor:
- For Sucrose: \( i = 1 \) → Least lowering of vapor pressure
- For Potassium Ferricyanide: \( i = 4 \) → Maximum lowering of vapor pressure
- For Potassium Sulfate: \( i = 3 \) → Intermediate lowering of vapor pressure

4. **Conclusion:**
- Since the lowering of vapor pressure is least for sucrose, it will have the maximum vapor pressure among the three solutions.
- Therefore, the maximum value of vapor pressure of the solution is that of **sucrose (A)**.

### Final Answer:
The maximum value of vapor pressure of the solution is that of **(A) 1m sucrose**.