A 1.17% solution of NaCl is isotonic with 7.2% solution of glucose. Calculate the Van’t Hoff factor of NaCl.

For isotonic solution, osmotic pressure should be same.
$\begin{array}{l}\therefore {\mathrm{\pi }}_{\left(\mathrm{NaCl}\right)}={\mathrm{\pi }}_{\left(\mathrm{glucose}\right)}\\ {\mathrm{iC}}_1\mathrm{RT}={\mathrm{C}}_2\mathrm{RT}\\ {\mathrm{iC}}_1={\mathrm{C}}_2\\ \mathrm{i}\left(\frac{1.17/58.5}{\mathrm{V}}\right)=\frac{7.2/180}{\mathrm{V}}\Rightarrow \mathrm{i}=\frac{7.2\times 58.5}{1.17\times 180}=2\end{array}$