Liquid Solution

Arrange the following solutions according to decreasing order of osmotic pressure under similar condition of temperature and assuming complete dissociation.

$$ \begin{array}{|c|l|} \hline \text { I. } & 0.2 \mathrm{~m} \mathrm{KCl} \\ \hline \text { II. } & 0.3 \mathrm{~m} \mathrm{MgSO}_4 \\ \hline \text { III. } & 0.1 \mathrm{~m} \mathrm{BaCl}_2 \\ \hline \text { IV. } & 0.5 \mathrm{~m} \mathrm{Al}_2\left(\mathrm{SO}_4\right)_3 \\ \hline \end{array} $$