Calculate $\%$ by mass of a $\mathrm{H}_2 \mathrm{O}_2$ solution that is 67.2 by volume.

Calculate the molality of the solution of nonvolatile solute if it freezes at $-0.36^{\circ} \mathrm{C}$.

$\left[K_{\mathrm{f}}\right.$ for solvent $\left.=1.86 \mathrm{~K} \mathrm{~kg} \mathrm{~mol}^{-1}\right]$

Calculate the vapour pressure of solution if relative lowering of vapour pressure and vapour pressure of pure solvent are 0.018 and 18 mm Hg respectively at 300 K .

Calculate the number of moles of nonvolatile solute dissolved in 0.5 kg solvent if molal elevation constant for solvent is $2 \mathrm{~kg} \mathrm{~K} \mathrm{~mol}^{-1} \left[\Delta \mathrm{T}_{\mathrm{b}}=0.8 \mathrm{~K}\right]$