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.

Sea water, which can be considered as a 6 molar $(6 \mathrm{M})$ solution of NaCl , has a density of $2 \mathrm{~g} \mathrm{~mL}^{-1}$. The concentration of dissolved oxygen $\left(\mathrm{O}_2\right)$ in sea water is 5.8 ppm . Then the concentration of dissolved oxygen $\left(\mathrm{O}_2\right)$ in sea water, is $x \times 10^{-4} \mathrm{~m}$.

$x=$ ___________. (Nearest integer)

Given: Molar mass of NaCl is $58.5 \mathrm{~g} \mathrm{~mol}^{-1}$

Molar mass of $\mathrm{O}_2$ is $32 \mathrm{~g} \mathrm{~mol}^{-1}$