If two substances $A$ and $B$ have $P_A^o : P_B^o = 2 : 1$ and have mole fraction in solution $1 : 3$,then the mole fraction of $A$ in the vapour phase is:

The vapour pressure will be lowest for

Lowering of vapour pressure due to a solute in $1 \, molal$ aqueous solution at $100 \, ^\circ C$ is ........ $torr$.

$1 \ mol$ each of the following solutes are taken in $5 \ mol$ of water:
$(i) \ NaCl$
$(ii) \ K_2SO_4$
$(iii) \ Na_3PO_4$
$(iv) \ \text{glucose}$
Assuming $100 \%$ ionization of the electrolytes,the relative decrease in vapor pressure will be in the order:

Calculate the vapour pressure of pure volatile liquid $B$ $(P_B^o)$ at a given temperature if the mole fraction of liquid $B$ $(x_B)$ is $0.4$ and the vapour pressure of pure volatile liquid $A$ $(P_A^o)$ is $400 \ mm \ Hg$. The total vapour pressure of the solution is $P_{total} = 600 \ mm \ Hg$. (in $mm \ Hg$)

Vapour pressure of pure water at $298 \, K$ is $23.8 \, mm \, Hg$. $50 \, g$ of urea $(NH_2CONH_2)$ is dissolved in $850 \, g$ of water. Calculate the vapour pressure of water for this solution and its relative lowering.