Which of the following solution will have highest freezing point?

Options

A. `2MNaCl` Solution
B. `1.5M AlCl_(3)` Solution
C. `1M Al_(2)(SO_(3))_(4)` Solution
D. `3M Urea` Solution

Explanation

To determine which solution will have the highest freezing point among the given options, we need to analyze the depression in freezing point for each solution. The depression in freezing point (ΔTf) is directly proportional to the molarity of the solution and the number of particles (ions or molecules) it dissociates into when dissolved in a solvent.

### Step-by-Step Solution:

1. **Understand the Concept of Depression in Freezing Point**:
- The depression in freezing point is given by the formula:
\[ \Delta T_f = i \cdot K_f \cdot m \]
- Where \(i\) is the van 't Hoff factor (number of particles the solute dissociates into), \(K_f\) is the freezing point depression constant, and \(m\) is the molality of the solution.

2. **Analyze Each Option**:
- We will calculate the product of molarity and the number of particles for each solution.

3. **Option 1: 2 M NaCl**:
- NaCl dissociates into Na⁺ and Cl⁻, so \(i = 2\).
- Molarity = 2 M.
- Therefore, \(i \cdot m = 2 \cdot 2 = 4\).

4. **Option 2: 1.5 M AlCl₃**:
- AlCl₃ dissociates into Al³⁺ and 3 Cl⁻, so \(i = 4\).
- Molarity = 1.5 M.
- Therefore, \(i \cdot m = 4 \cdot 1.5 = 6\).

5. **Option 3: 1 M Al₂(SO₄)₃**:
- Al₂(SO₄)₃ dissociates into 2 Al³⁺ and 3 SO₄²⁻, so \(i = 5\).
- Molarity = 1 M.
- Therefore, \(i \cdot m = 5 \cdot 1 = 5\).

6. **Option 4: 3 M Urea**:
- Urea does not dissociate in solution, so \(i = 1\).
- Molarity = 3 M.
- Therefore, \(i \cdot m = 1 \cdot 3 = 3\).

7. **Compare the Results**:
- Now we compare the values calculated:
- NaCl: 4
- AlCl₃: 6
- Al₂(SO₄)₃: 5
- Urea: 3
- The highest value of \(i \cdot m\) corresponds to the greatest depression in freezing point.

8. **Conclusion**:
- Since the depression in freezing point is lowest for the urea solution (3), it will have the highest freezing point.
- Therefore, the solution with the highest freezing point is **3 M Urea**.

### Final Statement:
Since the lowest depression in freezing point is in the urea solution, it will have the highest freezing point. Thus, the correct answer is **3 M Urea solution**.