A non-volatile, non-electrolyte solid solute when dissolved in 40 g of a solvent, the vapour pressure of the solvent decreased from 760 mm Hg to 750 mm Hg . If the same solution boils at 320 K , then the number of moles of the solvent present in the solution is $\_\_\_\_$ . (Nearest integer)

[Given: boiling point of the pure solvent $=319.5 \mathrm{~K}$,

$\mathrm{K}_{\mathrm{b}}$ of the solvent $=0.3 \mathrm{~K} \mathrm{~kg} \mathrm{~mol}^{-1}$ ]

Two liquids A and B form an ideal solution. At 320 K , the vapour pressure of the solution, containing 3 mol of $A$ and 1 mol of $B$ is 500 mm Hg . At the same temperature, if 1 mol of A is further added to this solution, vapour pressure of the solution increases by 20 mm Hg . Vapour pressure (in mm Hg ) of B in pure state is $\_\_\_\_$ . (Nearest integer)

The osmotic pressure of a living cell is 12 atm at 300 K. The strength of sodium chloride solution that is isotonic with the living cell at this temperature is ________ g L^-1. (Nearest integer)

Given : R = 0.08 L atm K^-1 mol^-1

Assume complete dissociation of NaCl

(Given: Molar mass of Na and Cl are 23 and 35.5 g mol^-1 respectively.)

A substance 'X' (1.5 g) dissolved in 150 g of a solvent 'Y' (molar mass = 300 g mol⁻¹) led to an elevation of the boiling point by 0.5 K. The relative lowering in the vapour pressure of the solvent 'Y' is ______ × 10⁻². (nearest integer)

[Given: K_b of the solvent = 5.0 K kg mol⁻¹]

Assume the solution to be dilute and no association or dissociation of X takes place in solution.