The vapor pressure of the solvent decreased by 10 mm Hg, when a non-volatile solute was added to the solvent. The mole fraction of the solute in the solution is 0.2. What should be the mole fraction of the solvent, if the decrease in vapor pressure of the solvent is required to be 20 mm Hg ?

Related Mcqs:

1. A very dilute solution is prepared by dissolving ‘x1’ mole of solute in ‘x2’ mole of a solvent. The mole fraction of solute is approximately equal to_________________?

   A. x1/x2
   B. x2/x1
   C. 1 – (x1/x2)
   D. 1/x2

2. Vapor pressure of a solution is proportional to (where, Sv and St are mole fraction of solvent and solute respectively) ?

   A. Sv
   B. 1/St
   C. St
   D. 1/Sv

3. The ratio of existing moles of vapor per mole of vapor free gas to the moles of vapor that would be present per mole of vapor free gas, if the mixture were saturated at the existing temperature & pressure, is termed as the_____________________?

   A. Relative humidity
   B. Relative saturation
   C. Percentage saturation
   D. None of these

4. Osmotic pressure of a dilute solution of a non volatile solute in a solvent obeying Raoult’s law is proportional to the_____________?

   A. Temperature
   B. Volume of solution
   C. Moles of non-volatile solute
   D. None of these

5. Addition of a non-volatile solute to a solvent produces a ______________ in its solvent?

   A. Freezing point elevation
   B. Boiling point depression
   C. Vapor pressure lowering
   D. All A., B. & C.

6. If the partial pressure of the solvent in the vapor phase is equal to the vapor pressure of the solvent at that temperature, then the system is said to be at its___________________?

   A. Bubble point
   B. Saturation temperature
   C. Dew point
   D. Both B. and C.

7. A solution is made by dissolving 1 kilo mole of solute in 2000 kg of solvent. The molality of the solution is_________________?

   A. 2
   B. 1
   C. 0.5
   D. 0.05

8. The vapour pressure of a solution (made by dissolving a solute in a solvent) is ____________ that of the pure solvent?

   A. Less than
   B. More than
   C. Equal to
   D. Either more or less; depends on the solvent

9. Osmotic pressure exerted by a solution prepared by dissolving one gram mole of a solute in 22.4 litres of a solvent at 0°C will be _______________ atmosphere?

   A. 0.5
   B. 1
   C. 1.5
   D. 2

10. What is the total pressure exerted by a mixture of 0.45 kg mole of benzene, 0.44 kg mole of toluene and 0.23 kg mole of o-xylene at 100°C, if their vapor pressures at 100°C are 1340, 560 and 210 mmHg respectively ?

    A. 756.2
    B. 780.5
    C. 801.5
    D. 880.5