' $x^{\prime} \mathrm{g}$ of urea (molar mass $60 \mathrm{gmol}^{-1}$ ) is completely dissolved in ' $y^{\prime} \mathrm{g}$ of pure water and the solution boiled at 373.202 K . If the boiling point of pure water at $1.01^3$ bar is 373.15 K , then $x: y$ is $\left(K_b\left(\mathrm{H}_2 \mathrm{O}\right)=0.52 \mathrm{~K} \mathrm{~kg} \mathrm{~mol}^{-1}\right)$

At 300 K , the osmotic pressure of a decinormal solution of sodium chloride is 4.82 atm . The degree of dissociation of sodium chloride is $x \times 10^{-2}$. The value of $x$ is $\left(R=0.082 \mathrm{~L} \mathrm{~atm} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}\right)$

If 2 g of NaOH is dissolved to make 200 mL solution at $25^{\circ} \mathrm{C}$, the molarity ( $M$ ) at $90^{\circ} \mathrm{C}$ is