Identify the correct statement:

Options

A. `0.1 M NaCl` and `0.1 M` glucose solution are isotonic
B. `0.1 M NaCl` and `0.3 M` glucose solution are isotonic
C. The boiling point of `0.1 m` aqueous urea solution is less the `0.1 m` aqueous KCl solution
D. The freezing point of `0.1 m` glucose solution is less than `0.1 m KCl` solution.

Explanation

To solve the question of identifying the correct statement regarding isotonic solutions and their properties, we will analyze each option step by step.

### Step-by-Step Solution:

1. **Understanding Isotonic Solutions**:
- Isotonic solutions have the same osmotic pressure, which depends on the concentration of solute particles in the solution. The van't Hoff factor (i) is crucial in determining this.

2. **Analyzing Option A**:
- **Statement**: 0.1 molar NaCl and 0.1 molar glucose solution are isotonic.
- **Van't Hoff Factor**:
- NaCl dissociates into 2 ions (Na⁺ and Cl⁻), so \( i = 2 \).
- Glucose does not dissociate, so \( i = 1 \).
- **Effective Concentration**:
- For NaCl: \( 0.1 \, \text{mol/L} \times 2 = 0.2 \)
- For glucose: \( 0.1 \, \text{mol/L} \times 1 = 0.1 \)
- Since the effective concentrations are different, **they are not isotonic**.

3. **Analyzing Option B**:
- **Statement**: 0.1 molar NaCl and 0.3 molar glucose solution are isotonic.
- **Van't Hoff Factor**:
- NaCl: \( i = 2 \) (as calculated before).
- For glucose at 0.3 molar: \( 0.3 \, \text{mol/L} \times 1 = 0.3 \).
- **Effective Concentration**:
- For NaCl: \( 0.1 \, \text{mol/L} \times 2 = 0.2 \)
- For glucose: \( 0.3 \, \text{mol/L} \times 1 = 0.3 \)
- Since the effective concentrations are different, **they are not isotonic**.

4. **Analyzing Option C**:
- **Statement**: The boiling point of 0.1 molal aqueous urea solution is less than that of 0.1 molal aqueous KCl.
- **Van't Hoff Factor**:
- Urea: \( i = 1 \)
- KCl: \( i = 2 \)
- **Boiling Point Elevation**:
- The boiling point elevation is proportional to the van't Hoff factor and concentration.
- Since KCl has a higher van't Hoff factor, **the boiling point of KCl will be higher than that of urea**.
- Therefore, this statement is **true**.

5. **Analyzing Option D**:
- **Statement**: The freezing point of 0.1 molar glucose solution is less than that of 0.1 molar KCl.
- **Van't Hoff Factor**:
- Glucose: \( i = 1 \)
- KCl: \( i = 2 \)
- **Freezing Point Depression**:
- The freezing point depression is also proportional to the van't Hoff factor and concentration.
- Since KCl has a higher van't Hoff factor, **the freezing point of KCl will be lower than that of glucose**.
- Therefore, this statement is **true**.

### Conclusion:
Both options C and D are correct statements.

### Final Answer:
The correct statements are **Option C** and **Option D**.

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