1.95 g of non-volatile and non-electrolyte solute dissolved in 100 g of benzene lowered the freezing point of it by 0.64 K .

The molar mass of the solute (in $\mathrm{g} \mathrm{mol}^{-1}$ )

$$ \left(K_f\left(\mathrm{C}_6 \mathrm{H}_6\right)=5.12 \mathrm{~K} \mathrm{~kg} \mathrm{~mol}^{-1}\right) $$

At $298 \mathrm{~K}, 0.714$ moles of liquid $A$ is dissolved in 5.555 moles of liquid $B$. The vapour pressure of the resultant solution is 475 torr. The vapour pressure of pure liquid $A$ at the same temperature is 280.7 torr. What is the vapour pressure of pure liquid $B$ in torr?

The resistance of a conductivity cell filled with 0.1 M KCl solution is $100 \Omega$. If the resistance of the same cell when filled with 0.2 M KCl solution is $520 \Omega$, the molar conductivity of 0.02 M solution (in $\mathrm{S} \mathrm{cm}^2 \mathrm{~mol}^{-1}$ ) is (Given: conductivity of 0.1 M KCl solution $=1.29 \mathrm{Sm}^{-1}$ )

In a first order reaction, the concentration of the reactant is reduced to $1 / 8$ of the initial concentration in 75 minutes. The $t_{1 / 2}$ of the reaction (in minutes) is $(\log 2=0.30, \log 3=0.47, \log 4=0.60)$