The elevation in boiling point will be maximum in

1 molal sodium chloride solution

The correct answer is option 2. 1 molal sodium chloride solution.

To determine which solution has the maximum elevation in boiling point, let’s use the formula for boiling point elevation and understand the role of the van't Hoff factor (\(i\)) and molality (\(m\)):

The elevation in boiling point (\(\Delta T_b\)) is given by:

\(\Delta T_b = i \cdot K_b \cdot m \)

where:

\(i\) = van't Hoff factor (number of particles the solute dissociates into),

\(K_b\) = ebullioscopic constant of the solvent (water in this case),

\(m\) = molality of the solution (moles of solute per kilogram of solvent).

Analysis of Each Solution

1. 1 molal glucose solution:

Glucose (C₆H₁₂O₆) does not dissociate in solution. Hence, the van't Hoff factor (\(i\)) is 1. Molality (\(m\)) is 1 molal.

Elevation in boiling point: \( \Delta T_b = i \cdot K_b \cdot m = 1 \cdot K_b \cdot 1 = K_b \).

2. 1 molal sodium chloride solution:

Sodium chloride (NaCl) dissociates into two ions: Na⁺ and Cl⁻. Hence, the van't Hoff factor (\(i\)) is 2. Molality (\(m\)) is 1 molal.

Elevation in boiling point: \( \Delta T_b = i \cdot K_b \cdot m = 2 \cdot K_b \cdot 1 = 2K_b \).

3. 0.1 molal glucose solution:

Glucose remains as one particle, so the van't Hoff factor (\(i\)) is 1. Molality (\(m\)) is 0.1 molal.

Elevation in boiling point: \( \Delta T_b = i \cdot K_b \cdot m = 1 \cdot K_b \cdot 0.1 = 0.1K_b \).

4. 0.1 molal sodium chloride solution:

Sodium chloride dissociates into two particles, so the van't Hoff factor (\(i\)) is 2. Molality (\(m\)) is 0.1 molal.

Elevation in boiling point: \( \Delta T_b = i \cdot K_b \cdot m = 2 \cdot K_b \cdot 0.1 = 0.2K_b \).

Comparison of Elevations

To determine which solution has the maximum boiling point elevation:

1 molal glucose solution: \( \Delta T_b = K_b \)

1 molal sodium chloride solution: \( \Delta T_b = 2K_b \)

0.1 molal glucose solution: \( \Delta T_b = 0.1K_b \)

0.1 molal sodium chloride solution: \( \Delta T_b = 0.2K_b \)

The solution with the highest boiling point elevation is the one with the highest value of \( \Delta T_b \), which is: 1 molal sodium chloride solution: \( \Delta T_b = 2K_b \)

Conclusion

The maximum elevation in boiling point occurs in the solution with the highest van't Hoff factor and molality. In this case, the **1 molal sodium chloride solution** has the highest elevation due to its higher van't Hoff factor (2) and the same molality as the 1 molal glucose solution.

Thus, the correct answer is: 2. 1 molal sodium chloride solution.