Which of the following aqueous solutions having same molality exhibits maximum boiling point elevation? (Assume complete dissociation)

Calculate the mole fraction of pure liquid $B$ in solution if total vapour pressure of solution, vapour pressure of pure liquid A and vapour pressure of pure liquid B are 500 mm Hg , 400 mm Hg and 575 mm Hg respectively at given temperature.

What is the numerical value of osmotic pressure of 1 M urea solution if numerical value of osmotic pressure of 0.5 M urea solution is ' $x$ '?

Calculate vapour pressure of volatile liquid A at given temperature if mole fraction and vapour pressure of volatile liquid B are 0.4 and 900 mm Hg respectively [ $\mathrm{P}_{\text {total }}=600 \mathrm{~mm} \mathrm{Hg}$ ]