Compreshension -I
The experimental values of colligative properties of many solutes in solution resembles calculated value of colligative properties.
However in same cases, the experimental value of colligative property differ widely than those obtained by calculation. Such experimental values of colligative properties are known as Abnormal values of colligative properties are :
(i) Dissociation of solute : It increases the colligative properties.
(ii) Association of solute : It decreases the colligative properties
e.g. : Dimerisation of acetic acid in benzene
4 different 100 ml solutions are prepared by mixing 1 gram each of NaCl `(NH_(2))_(2)CO.Na_(2)SO_(4)` and `K_(4)[Fe(CN)_(6)]` at temperature T. Correct order of osmotic pressure is

Options

A. `(NH_(2))_(2)CO` solution `gt` NaCl solution `gt Na_(2)SO_(4)` solution `gt K_(4)[Fe(CN)_(6)]` solution
B. NaCl solution `gt Na_(2)SO_(4)` solution `gt (NH_(2))_(2)CO` solution `gt K_(4)[Fe(CN)_(6)]` solution
C. `K_(4)[Fe(CN)_(6)]` solution `gt Na_(2)SO_(4)` solution `gt `NaCl solution `gt (NH_(2))_(2)CO` solution
D. `Na_(2)SO_(4)` solution `gt (NH_(2))_(2)CO` solution `gt `NaCl solution `gt K_(4)[Fe(CN)_(6)]` solution

Answer

To solve the problem regarding the osmotic pressure of the given solutions, we need to analyze the dissociation of each solute and calculate the van 't Hoff factor (i) for each one. The osmotic pressure (π) of a solution can be expressed 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

Since all solutions are prepared with the same mass (1 gram) in 100 ml of solution, we can focus on the van 't Hoff factor (i) to determine the order of osmotic pressure.

### Step-by-step Solution:

1. **Identify the solutes and their dissociation:**
- **NaCl**: Dissociates into 2 ions: Na⁺ and Cl⁻. Thus, \( i = 2 \).
- **NH₂COONa (Sodium formate)**: This is a non-ionic compound that does not dissociate in solution. Thus, \( i = 1 \).
- **Na₂SO₄**: Dissociates into 3 ions: 2 Na⁺ and SO₄²⁻. Thus, \( i = 3 \).
- **K₄[Fe(CN)₆]**: Dissociates into 5 ions: 4 K⁺ and 1 [Fe(CN)₆]⁴⁻. Thus, \( i = 5 \).

2. **Calculate the van 't Hoff factor (i) for each solute:**
- NaCl: \( i = 2 \)
- NH₂COONa: \( i = 1 \)
- Na₂SO₄: \( i = 3 \)
- K₄[Fe(CN)₆]: \( i = 5 \)

3. **Determine the order of osmotic pressure:**
Since osmotic pressure is directly proportional to the van 't Hoff factor (i), we can arrange the solutes based on their i values:
- K₄[Fe(CN)₆] (i = 5)
- Na₂SO₄ (i = 3)
- NaCl (i = 2)
- NH₂COONa (i = 1)

4. **Write the correct order of osmotic pressure:**
The correct order of osmotic pressure from highest to lowest is:
\[ K₄[Fe(CN)₆] > Na₂SO₄ > NaCl > NH₂COONa \]

### Final Answer:
The correct order of osmotic pressure is:
\[ K₄[Fe(CN)₆] > Na₂SO₄ > NaCl > NH₂COONa \]