A solution is prepared by dissolving 2.5g of a non-volatile solute in 100g of water. The vapor pressure of the solution is found to be 22.87 Torr at $25^\circ C$. If the vapor pressure of pure water is 23.76 Torr at the same temperature, what is the molar mass of the solute (in g/mol)?

Weight of ${\rm{FeS}}{{\rm{O}}_4}\left( {{\rm{mol}}{\rm{.wt}}{\rm{.}} = 152} \right)$ oxidized by 200 mL of 1 $N$ ${\rm{KMn}}{{\rm{O}}_4}$ solution is :