Which of the following solutions has the maximum freezing point?

Options

A. 1 molal of NaCl solution
B. 1 molal of KCl solution
C. `1 molal of CaCl_(2)` solution
D. 1 molal of urea solution

Explanation

To determine which solution has the maximum freezing point, we need to understand the concept of freezing point depression (ΔTf). The freezing point depression is given by the formula:

\[ \Delta T_f = i \cdot K_f \cdot m \]

Where:
- \( \Delta T_f \) = depression in freezing point
- \( i \) = van 't Hoff factor (number of particles the solute dissociates into)
- \( K_f \) = freezing point depression constant (depends on the solvent)
- \( m \) = molality of the solution

### Step-by-Step Solution:

1. **Identify the van 't Hoff factors for each solute**:
- For NaCl: It dissociates into 2 ions (Na⁺ and Cl⁻), so \( i = 2 \).
- For KCl: It also dissociates into 2 ions (K⁺ and Cl⁻), so \( i = 2 \).
- For CaCl₂: It dissociates into 3 ions (1 Ca²⁺ and 2 Cl⁻), so \( i = 3 \).
- For Urea: It does not dissociate, so \( i = 1 \).

2. **Compare the van 't Hoff factors**:
- NaCl: \( i = 2 \)
- KCl: \( i = 2 \)
- CaCl₂: \( i = 3 \)
- Urea: \( i = 1 \)

3. **Determine the effect on freezing point**:
- The greater the value of \( i \), the greater the depression in freezing point (ΔTf).
- Therefore, the solution with the lowest \( i \) will have the highest freezing point.

4. **Identify the solution with the lowest van 't Hoff factor**:
- Urea has the lowest van 't Hoff factor (\( i = 1 \)).

5. **Conclusion**:
- Since Urea has the lowest van 't Hoff factor, it will cause the least depression in freezing point, thus having the maximum freezing point among the given solutions.

### Final Answer:
The solution with the maximum freezing point is the solution of **Urea**.