The mass of a non-volatile, non-electrolyte solute (molar mass = 50 g mol^-1 ) needed to be dissolved in 114 g octane to reduce its vapour pressure to 75%, is :

For 1 molal aqueous solution of the following compounds, which one will show the highest freezing point?

Two 5 molal solutions are prepared by dissolving a non-electrolyte non-volatile solute separately in the solvents X and Y. The molecular weights of the solvents are M_x and M_y, respectively where M_x = $${3 \over 4}$$ My. The relative lowering of vapor pressure of the solution in X is ''m'' times that of the solution in Y. Given that the number of moles of solute is very small in comparison to that of the solvent, the value of ''m'' is :

A solution is prepared by mixing 8.5 g of CH₂Cl₂ and 11.95 g of CHCl₃ . If vapour pressure of CH₂Cl₂ and CHCl₃ at 298 K are 415 and 200 mmHg respectively, the mole fraction of CHCl₃ in vapour form is : (Molar mass of Cl = 35.5 g mol⁻¹)