$1.02 \mathrm{\%}$ solution of glycerine and $2 \mathrm{\%}$ solution glucose are isotonic. If molecular weight of glucose is 180, then find the molecular weight of glycerine. 

As both solutions are isotonic, therefore their osmotic pressure value is the same.

$$\begin{gathered} {\mathrm{\pi }}_{\mathrm{glycerine}}={\mathrm{\pi }}_{\mathrm{glucose}} \\ {\mathrm{C}}_{\mathrm{glycerine}}\mathrm{RT}={\mathrm{C}}_{\mathrm{glucose}}\mathrm{RT} \\ {\mathrm{C}}_{\mathrm{glycerine}}={\mathrm{C}}_{\mathrm{glucose}} \end{gathered}$$

1.02% means that 1.02 g of glycerine present in 100 ml. Similarly, 2% means that 2 g of glucose present in 100 ml.

$$\begin{gathered} {\mathrm{C}}_{\mathrm{glycerine}}={\mathrm{C}}_{\mathrm{glucose}} \\ \frac{1.02\times 1000}{\mathrm{molecular} \mathrm{weight} \mathrm{of} \mathrm{glycerine}\times 100}=\frac{2\times 1000}{180\times 100} \\ \mathrm{molecular} \mathrm{weight} \mathrm{of} \mathrm{glycerine}=91.8 \end{gathered}$$