At $27^{\circ} \mathrm{C}$, a solution containing $2.5 \mathrm{~g}$ of solute in $250.0 \mathrm{~mL}$ of solution exerts an osmotic pressure of $400 \mathrm{~Pa}$. The molar mass of the solute is ___________ $\mathrm{g} \mathrm{~mol}^{-1}$ (Nearest integer)

(Given : $\mathrm{R}=0.083 \mathrm{~L} \mathrm{~bar} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}$)