Consider following solutions: (I) I M glucose(aq) (II) 1 M sodium choride(aq)
(III) 1 M acetic acid in benzene (IV) 1 M ammonium phosphate (aq)

Options

A. all are isotonic solutions
B. III is hypotonic of I, II, IV
C. I, II, Ivare hypertonic of III
D. IV is hypertonic I, II, III

Answer

To determine the relationship of osmotic pressure among the given solutions, we need to analyze each solution based on its dissociation in water and the van 't Hoff factor (i). The osmotic pressure (π) can be calculated using the formula:

\[ \pi = iCRT \]

Where:
- \( \pi \) = osmotic pressure
- \( i \) = van 't Hoff factor (number of particles the solute dissociates into)
- \( C \) = molarity of the solution
- \( R \) = ideal gas constant
- \( T \) = temperature in Kelvin

Given that all solutions are 1 M, we can focus on the van 't Hoff factor (i) for each solute.

### Step 1: Analyze each solution

1. **Glucose (C₆H₁₂O₆)**:
- Glucose does not dissociate in solution.
- \( i = 1 \)

2. **Sodium Chloride (NaCl)**:
- Sodium chloride dissociates into two ions: Na⁺ and Cl⁻.
- \( i = 2 \)

3. **Acetic Acid (CH₃COOH)**:
- Acetic acid is a weak acid and does not completely dissociate in benzene.
- For practical purposes, we can assume \( i \approx 1 \) because it only partially ionizes and is not in water.

4. **Ammonium Phosphate (NH₄₃PO₄)**:
- Ammonium phosphate dissociates into four ions: 3 NH₄⁺ and 1 PO₄³⁻.
- \( i = 4 \)

### Step 2: Calculate the osmotic pressure for each solution

Using the values of \( i \):

- **Osmotic Pressure of Glucose**:
\[ \pi_{glucose} = 1 \cdot 1 \cdot CRT = CRT \]

- **Osmotic Pressure of Sodium Chloride**:
\[ \pi_{NaCl} = 2 \cdot 1 \cdot CRT = 2CRT \]

- **Osmotic Pressure of Acetic Acid**:
\[ \pi_{acetic\ acid} \approx 1 \cdot 1 \cdot CRT = CRT \]

- **Osmotic Pressure of Ammonium Phosphate**:
\[ \pi_{ammonium\ phosphate} = 4 \cdot 1 \cdot CRT = 4CRT \]

### Step 3: Compare the osmotic pressures

Now we can compare the osmotic pressures:

- \( \pi_{glucose} = CRT \)
- \( \pi_{NaCl} = 2CRT \)
- \( \pi_{acetic\ acid} \approx CRT \)
- \( \pi_{ammonium\ phosphate} = 4CRT \)

### Step 4: Conclusion on osmotic pressure

From the calculations, we can rank the solutions based on their osmotic pressures:

1. Ammonium Phosphate (highest osmotic pressure)
2. Sodium Chloride
3. Glucose and Acetic Acid (lowest osmotic pressure)

Thus, the order of osmotic pressure from highest to lowest is:
- Ammonium Phosphate > Sodium Chloride > Glucose = Acetic Acid