Which of the following aqueous solution will exhibit highest boiling point?
1. \(0.01 \mathrm{M} ~\mathrm{Na}_2 \mathrm{SO}_4 \)
2. \(0.015 \text M~\mathrm{C}_6 \mathrm{H}_{12} \mathrm{O}_6 \)
3. \(0.01 \text {M Urea} \)
4. \(0.01 \mathrm{M} ~\mathrm{KNO}_3\)