Calculate the solubility of a gas in water at $$0.8 \mathrm{~atm}$$ and $$25^{\circ} \mathrm{C}$$.

[Henry's law constant is $$6.85 \times 10^{-4} \mathrm{~mol} \mathrm{~dm}^{-3} \mathrm{~atm}^{-1}$$ ]

Identify the concentration of the solution from following so that values of ,$$\Delta \mathrm{T}_{\mathrm{f}}$$ and $$\mathrm{K}_{\mathrm{f}}$$ are same.

Calculate the amount of solute dissolved in 160 gram solvent that boils at $$85^{\circ} \mathrm{C}$$, the molar mass of solute is $$120 \mathrm{~g} \mathrm{~mol}^{-1}$$. $$\left(\mathrm{K}_{\mathrm{b}}\right.$$ for solvent $$=2.7^{\circ} \mathrm{C} \mathrm{~kg} \mathrm{~mol}^{-1}$$ and boiling point of solvent $$=76^{\circ} \mathrm{C}$$)

The solution containing $$3 \mathrm{~g}$$ urea (molar mass 60 ) per $$\mathrm{dm}^3$$ of water and another solution containing $$4.5 \mathrm{~g}$$ of solute $$\mathrm{A}$$ per $$\mathrm{dm}^3$$ boils at same temperature, then what is molar mass of $$\mathrm{A}$$ ?