Arrange the following aqueous solutions in the order of their increasing boiling points.
I. ${10}^{-2}\mathrm{MNaCl}$
II.${10}^{-3}\mathrm{M} {\mathrm{MgCl}}_2$
III.${10}^{-4}\mathrm{M} \mathrm{Urea}$
IV.${10}^{-4}\mathrm{M} \mathrm{NaCl}$

More the value of i, more will be the elevation in boiling point. Again, more dilute solution has low boiling point. Hence, increasing order of boiling points is:
$$\begin{gathered} {10}^{-4}\mathrm{m} \mathrm{Urea} <{10}^{-4}\mathrm{M} \mathrm{NaCl}<{10}^{-3}\mathrm{M} {\mathrm{MgCl}}_2 <{10}^{-2}\mathrm{M} \mathrm{NaCl} \\ (\mathrm{i}=1) (\mathrm{i}=2) (\mathrm{i}=3) (\mathrm{i}=2) \end{gathered}$$