The Osmotic pressure of solution containing 4.0g of solute (molar mass 246) per litre at 27°C is (R = 0.082L atm ${\mathrm{k}}^{-1}{ \mathrm{mol}}^{-1}$) :

$$\begin{gathered} Weight of solute = 4g \\ molar mass of solute =246gm/mol \\ R = 0.082L atm/k/mol \\ Osmotic pressure \left(\mathrm{\pi }\right) = \frac{W}{M\times V}\times R\times T \\ = \left(\frac{4}{246\times 0.082}\right)\times 0.082\times 300 \mathrm{K} = 0.4 \mathrm{atm} \end{gathered}$$

Therefore, the correct option is C