How many grams of sucrose $\left({\mathrm{C}}_{12}{\mathrm{H}}_{22}{\mathrm{O}}_{11}\right)$ must be dissolved in $90 \mathrm{g}$ of water to produce a solution over which the relative humidity is $80\%$? Assume the solution is ideal. Give your answer after dividing by $10$.

Methanol and ethanol form nearly ideal solutions at $300\mathrm{K}$. A solution is made by mixing of $32\mathrm{g}$ Methanol and ethanol the partial pressure $23\mathrm{g}$ ethanol. Calculate the partial pressure of its constituents and the total pressure of the solution.

$(\mathrm{at} 300 \mathrm{K}; {\mathrm{p}}^{\circ } ({\mathrm{CH}}_3\mathrm{OH}) = 90 \mathrm{mm} \mathrm{Hg}, {\mathrm{p}}^{\circ }({\mathrm{C}}_2{\mathrm{H}}_5\mathrm{OH}) = 51 \mathrm{mm} \mathrm{Hg})$.