Relative Lowering of Vapour Pressure — Prelims Questions

The vapour pressure of pure benzene at a certain temperature is $0.850,\text{bar}$. A non-volatile, non-electrolyte solid weighing $0.5,\text{g}$ when added to $39,\text{g}$ of benzene (molar mass $78,\text{g/mol}$) results in a solution with a vapour pressure of $0.845,\text{bar}$. What is the molar mass of the solid substance?

Which of the following solutions will have the lowest vapour pressure at a given temperature?

At $300,\text{K}$, the vapour pressure of a solution containing $1,\text{mole}$ of a non-volatile solute in $4,\text{moles}$ of water is $P_s$. If the vapour pressure of pure water at $300,\text{K}$ is $P^0$, what is the ratio $rac{P^0}{P_s}$?

If the relative lowering of vapour pressure for an aqueous solution is $0.02$, what is the mole fraction of the solvent in this solution?

The vapour pressure of pure water at $298,\text{K}$ is $23.75,\text{mmHg}$. The vapour pressure of an aqueous solution containing $5,\text{g}$ of urea (molar mass $60,\text{g/mol}$) dissolved in $100,\text{g}$ of water (molar mass $18,\text{g/mol}$) is approximately:

Which of the following statements is INCORRECT regarding relative lowering of vapour pressure?