Which one of the following aqueous solutions will exhibit highest elevation in boiling point?

Options

A. 0.015 M urea
B. 0.01 M `KNO_(3)`
C. `0.10 M Na_(2) SO_(4)`
D. 0.015 m glucose

Answer

To determine which aqueous solution exhibits the highest elevation in boiling point, we can follow these steps:

### Step 1: Understand the Concept of Boiling Point Elevation
The elevation in boiling point (\( \Delta T_b \)) is a colligative property that depends on the number of solute particles in a solution. The formula for boiling point elevation is given by:
\[ \Delta T_b = K_b \times m \times i \]
where:
- \( \Delta T_b \) = elevation in boiling point
- \( K_b \) = ebullioscopic constant (specific to the solvent)
- \( m \) = molality of the solution
- \( i \) = Van't Hoff factor (number of particles the solute dissociates into)

### Step 2: Analyze Each Solution
We need to evaluate the Van't Hoff factor (\( i \)) for each solute given in the options:

1. **Urea**: Urea is a non-electrolyte and does not dissociate in solution. Therefore, \( i = 1 \).

2. **KNO3 (Potassium Nitrate)**: KNO3 dissociates into \( K^+ \) and \( NO_3^- \). Thus, \( i = 2 \).

3. **Na2SO4 (Sodium Sulfate)**: Na2SO4 dissociates into \( 2 Na^+ \) and \( SO_4^{2-} \). Therefore, \( i = 3 \).

4. **Glucose**: Similar to urea, glucose is a non-electrolyte and does not dissociate. Hence, \( i = 1 \).

### Step 3: Compare the Van't Hoff Factors
Now we can summarize the Van't Hoff factors for each solution:
- Urea: \( i = 1 \)
- KNO3: \( i = 2 \)
- Na2SO4: \( i = 3 \)
- Glucose: \( i = 1 \)

### Step 4: Determine the Highest Elevation in Boiling Point
Since the elevation in boiling point is directly proportional to the Van't Hoff factor (\( i \)), the solution with the highest \( i \) will have the highest elevation in boiling point.

From our analysis:
- The highest \( i \) value is for Na2SO4, which is \( 3 \).

### Conclusion
Thus, the aqueous solution that will exhibit the highest elevation in boiling point is:
**0.1 molar Na2SO4 (Option C)**.

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