Answer: The vapor pressure of a solution in which the mole fraction of the solute is 0.200 is 80.0 torr
Explanation:
As the relative lowering of vapor pressure is directly proportional to the amount of dissolved solute.
The formula for relative lowering of vapor pressure will be,
[tex]\frac{p^o-p_s}{p^o}=i\times x_2[/tex]
where,
[tex]p^0[/tex]= vapor pressure of pure solvent = 100.0 torr
[tex]p_s[/tex] = vapor pressure of solution = ?
i = Van'T Hoff factor = 1 for nonvolatile, nonelectrolyte solute
[tex]x_2[/tex] = mole fraction of solute = 0.200
[tex]\frac{100.0-p_s}{100.0}=1\times 0.200[/tex]
[tex]p_s=80.0torr[/tex]
The vapor pressure of a solution in which the mole fraction of the solute is 0.200 is 80.0 torr