At $300 \ K$,an ideal solution is formed by mixing $460 \ g$ of toluene with $390 \ g$ of benzene. If the vapour pressure of pure toluene and pure benzene at $300 \ K$ are $32 \ mm$ and $40 \ mm$ respectively,the mole fraction of toluene in the vapour phase is:

$A$ solution of urea (molar mass $60 \ g \ mol^{-1}$) boils at $100.20^{\circ}C$ at atmospheric pressure. If $K_{f}$ and $K_{b}$ for water are $1.86$ and $0.512 \ K \ kg \ mol^{-1}$ respectively,the freezing point of the solution will be:

An aqueous solution freezes at $-2.55 \ ^oC$. What is its boiling point in $^oC$?
[$K_b(H_2O) = 0.52 \ K \ kg \ mol^{-1}, K_f(H_2O) = 1.86 \ K \ kg \ mol^{-1}$]

Give examples of ideal solutions and azeotropes.

For a dilute solution containing $2.5 \ g$ of a non-volatile non-electrolyte solute in $100 \ g$ of water,the elevation in boiling point at $1 \ atm$ pressure is $2 \ ^\circ C$. Assuming the amount of solute is much lower than the amount of solvent,the vapour pressure $(mm \ Hg)$ of the solution is: (take $K_b = 0.76 \ K \ kg \ mol^{-1}$)

When $0.1 \, m$ $CH_3COOH$ is present in a solvent,it shows an elevation in boiling point of $0.75 \, ^oC$. The acid dissociation constant $(K_a)$ will be: (Given: $K_b = 5 \, K \, kg \, mol^{-1}$)