A: Boiling point of 0.1 M solution of NaCl is higher than that of 0.1 M solution of urea.
R: Greater the value of Van't Hoff factor, greater the elevation in boiling point of solution containing non volatile solute.

Answer

To solve the question, we need to analyze the two assertions and their relationship to each other regarding the boiling points of solutions.

### Step-by-Step Solution:

1. **Understanding the Assertion (A)**:
- The assertion states that the boiling point of a 0.1 M solution of NaCl is higher than that of a 0.1 M solution of urea.
- NaCl is an ionic compound that dissociates in solution to produce ions, while urea is a non-electrolyte that does not dissociate.

2. **Dissociation of NaCl**:
- When NaCl dissolves in water, it dissociates into two ions: Na⁺ and Cl⁻.
- Therefore, for a 0.1 M solution of NaCl, the effective concentration of particles in solution is 0.1 M Na⁺ + 0.1 M Cl⁻ = 0.2 M total ions.

3. **Understanding Urea**:
- Urea does not dissociate into ions when dissolved in water; it remains as whole molecules.
- Thus, a 0.1 M solution of urea has an effective concentration of particles equal to 0.1 M.

4. **Van't Hoff Factor (i)**:
- The Van't Hoff factor (i) is a measure of the number of particles into which a solute dissociates in solution.
- For NaCl, i = 2 (since it dissociates into 2 ions).
- For urea, i = 1 (since it does not dissociate).

5. **Boiling Point Elevation**:
- The elevation in boiling point (ΔTb) is directly proportional to the Van't Hoff factor and the molality of the solution:
\[ \Delta T_b = i \cdot K_b \cdot m \]
- Here, Kb is the ebullioscopic constant of the solvent, and m is the molality of the solution.

6. **Comparing the Two Solutions**:
- For NaCl:
\[ \Delta T_b = 2 \cdot K_b \cdot 0.1 \]
- For urea:
\[ \Delta T_b = 1 \cdot K_b \cdot 0.1 \]
- Since the value of ΔTb for NaCl is higher than that for urea, the boiling point of the NaCl solution is indeed higher.

7. **Conclusion**:
- Both the assertion (A) and the reason (R) are correct. The assertion is true because NaCl produces more particles in solution compared to urea, leading to a higher boiling point. The reason is also correct as it explains that a higher Van't Hoff factor results in a greater elevation in boiling point.

### Final Answer:
- Assertion (A) is true: The boiling point of a 0.1 M solution of NaCl is higher than that of a 0.1 M solution of urea.
- Reason (R) is true: Greater the value of Van't Hoff factor, greater the elevation in boiling point of solution containing non-volatile solute.