Calculate the molar mass of nonvolatile solute when 4 g of it is dissolved in 100 g solvent that boils at 319.4 K [$K_b$ = 2.4 K kg $\text{mol}^{-1}$; B.P of pure solvent = 319 K]

The normal boiling point of Ethyl acetate is $77^\circ\text{C}$. A solution of non-volatile non-electrolyte solute in ethyl acetate boils at $78^\circ\text{C}$. $K_b$ for ethyl acetate is $2.77\ ^\circ\text{C kg mol}^{-1}$. What is the molality of the solution ?

18 g of glucose (molar mass = 180 g/mol) is dissolved in water to prepare 500 ml solution at $15^\circ\text{C}$. Calculate the osmotic pressure of the solution. [$R = 0.0821\ \text{L atm K}^{-1}\ \text{mol}^{-1}$]

For a binary solution, when a nonvolatile nonelectrolyte solute is dissolved in solvent, the vapour pressure of solvent decreases by 20 % . what is mole fraction of solvent in solution ?