Among the following substances,the lowest vapour pressure is exerted by

At a given temperature,the vapour pressure of pure water is $25 \ mm$ and the vapour pressure of a dilute solution of urea is $24.5 \ mm$. The molality of the solution is:

What will be the molar mass of a non-volatile solute if the vapour pressure of pure benzene is $450 \ mm \ Hg$ and it decreases to $400 \ mm \ Hg$ when $1.5 \ g$ of the solute is added to $30 \ g$ of benzene? (Atomic mass: $C=12, H=1$)

$A$ mixture of $3.0 \ mol$ of $Na_2O$ and $1.5 \ mol$ of $KO_2$ is dissolved in $1000 \ mL$ of water. The vapour pressure of the solution in $Torr$, at $100^{\circ}C$ is:

If $P_0$ and $P_s$ are the vapour pressures of the solvent and its solution respectively,and $N_1$ and $N_2$ are the mole fractions of the solvent and solute respectively,then which of the following is correct?

The vapour pressure of a high boiling liquid is . . . . . . compared to the vapour pressure of a low boiling liquid.