For a dissociated solute in solution, the value of van't Hoff factor is :
1) zero
2) one
3) greater than one
4) less than one

Options

A. zero
B. one
C. greater than one
D. less than one

Answer

To determine the value of the van't Hoff factor (i) for a dissociated solute in solution, we can follow these steps:

### Step 1: Understand the van't Hoff factor
The van't Hoff factor (i) is defined as the ratio of the number of particles in solution after dissociation to the number of particles before dissociation. It is represented mathematically as:

\[ i = \frac{\text{Number of particles after dissociation}}{\text{Number of particles before dissociation}} \]

### Step 2: Identify the nature of the solute
For a dissociated solute, such as an electrolyte (e.g., NaCl), the solute breaks into its constituent ions when dissolved in a solvent. For example, NaCl dissociates into Na⁺ and Cl⁻ ions.

### Step 3: Calculate the van't Hoff factor for a dissociated solute
- Before dissociation: 1 mole of NaCl (which counts as 1 particle).
- After dissociation: 1 mole of NaCl produces 1 mole of Na⁺ and 1 mole of Cl⁻, resulting in a total of 2 particles.

Thus, for NaCl:
\[ i = \frac{2 \text{ (after)}}{1 \text{ (before)}} = 2 \]

### Step 4: Generalize for other dissociated solutes
For any strong electrolyte that completely dissociates, the van't Hoff factor will be greater than 1. Even for weak electrolytes, although they do not fully dissociate, the van't Hoff factor will still be greater than 1 due to the presence of some dissociated ions.

### Conclusion
Therefore, for a dissociated solute in solution, the value of the van't Hoff factor is always greater than 1.

### Final Answer
The correct option is **3) greater than one**.

---