It is given that:

Volume of water $(\mathrm{V})=450 \mathrm{~mL}=0.45 \mathrm{~L}$

Temperature (T) $=37+273=310 \mathrm{~K}$

moles of the polymer, $\mathrm{n}=\frac{1}{185000} \mathrm{~mol}$

We know that:

Osmotic pressure, $\pi=\frac{n}{V} R T$

$=\frac{1}{185000}~\text{mol}\times \frac{1}{0.45~\text{L}}\times 8.314\times {{10}^{3}}\text{PaL}{{\text{K}}^{-1}}~\text{mo}{{\text{l}}^{-1}}\times 310~\text{K}$

$=30.98~\text{Pa}$ $=31~\text{Pa (approx) }$