When 25 grams of a non-volatile solute is dissolved in 100 grams of water, the vapour pressure is lowered by $2.25 \times 10^{-1}\;mm$ If the vapour pressure of water at $20^{\circ}$ is 17.5\;mm$ What is the molecular weight of the solute?

Question

\[\begin {array} {1 1} (1)\;206 & \quad (2)\;302 \\ (3)\;350 & \quad (4)\;276 \end {array}\]