An aqueous solution contains $6\%$ and $4\%$ by weight of a weak acid $(HA)$ and urea respectively. If the depression in freezing point is $\frac{13.6}{3} \, ^{\circ}C$,calculate the $K_a$ of $HA$. [Given: $K_f = 1.8 \, K \, kg/mol$,Molecular weight of $HA = 60$,$d_{solution} = 1 \, g/mL$]

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 concentration of solute is much lower than the concentration of solvent,the vapour pressure ($mm$ of $Hg$) of the solution is (take $K_{b}=0.76 \ K \ kg \ mol^{-1}$)

Give examples of ideal solutions and azeotropes.

In the depression of freezing point experiment:
$A.$ Vapour pressure of the solution is less than that of pure solvent
$B.$ Vapour pressure of the solution is more than that of pure solvent
$C.$ Only solute molecules solidify at the freezing point
$D.$ Only solvent molecules solidify at the freezing point

$25 \ mL$ of an aqueous solution of $KCl$ was found to require $20 \ mL$ of $1 \ M \ AgNO_3$ solution when titrated using $K_2CrO_4$ as an indicator. What is the depression in freezing point of $KCl$ solution of the given concentration? (Nearest integer). Given: $K_f = 2.0 \ K \ kg \ mol^{-1}$. Assume: $(1)$ $100 \%$ ionization and $(2)$ density of the aqueous solution as $1 \ g \ mL^{-1}$.

$A$ Beckmann thermometer is used to measure: