A solution is obtained by mixing $300 \mathrm{g}$ of $25\%$ solution and $400 \mathrm{g}$ of $40\%$ solution by mass. Calculate the mass percentage of the resulting solution.

Calculate the amount of benzoic acid (${\mathrm{C}}_6{\mathrm{H}}_5\mathrm{COOH}$) required for preparing $250 \mathrm{mL}$, of $0.15 \mathrm{M}$ solution in methanol.

Vapour pressure of water is $12.3 \mathrm{kPa}$ at $300 \mathrm{K}$. Calculate vapour pressure of $1$ molal solution of a non-volatile solute in it.

A solution containing $18 \mathrm{g}$ of non-volatile solute in $200 \mathrm{g}$ of water freezes at $272.07 \mathrm{K}$. Calculate the molecular mass of the solute in $\mathrm{g}/\mathrm{mol}$ (Water freezes at $273 \mathrm{K}$ and its ${\mathrm{K}}_{\mathrm{f}}=1.86 \mathrm{K} \mathrm{kg} {\mathrm{mol}}^{-1}$).

A $5\%$ solution of ${\mathrm{CaCl}}_2$ at $0°\mathrm{C}$ developed an osmotic pressure of $15$ atmosphere. Calculate the degree of dissociation.

A solution of $2.4 \mathrm{g}$ of a substance in $25 \mathrm{g}$ water boiled at $100.8°\mathrm{C}$ at $1 \mathrm{atm}$ pressure. Calculate the molecular mass of the substance  (in $\mathrm{g}/\mathrm{mol}$). (Boiling elevation constant for water$=0.52°\mathrm{C}$ per $1000 \mathrm{g}$ of it).