A solution containing 30 g of non-volatile solute exactly in 90 g of water has a vapour pressure of 2.8 kPa at 298 K. Further, 18 g of water is then added to the solution and the new vapour pressure becomes 2.9 kPa at 298 K. Calculate: molar mass of the solute

Question

$\begin{array}{1 1}23g mol^{-1}\\43g mol^{-1}\\33g mol^{-1}\\53g mol^{-1}\end{array} $