An ideal mixture of liquids A and B with 2 moles of A and 2 moles of B has a total vapour pressure of 1 atm at a certain temperature. Another mixture with 1 mole of A and 3 moles of B has a vapour pressure greater than 1 atm. But if 4 moles of C are added to the second mixture, the vapour pressure comes down to 1 atm. Vapour pressure of C, Pc° = 0.8 atm. Calculate the vapour pressures of pure A and pure B.

(1) PA° = 1.4 atm, PB° = 0.7 atm

(2) PA = 1.2 atm, PB° = 0.6 atm

(3) PA = 1.4 atm, PB° = 0.6 atm

(4) PA° = 0.6 atm, PB° = 1.4 atm

Concept Questions :-

Dalton’s Law of Partial Pressure/ Henry"s law
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Difficulty Level:

A sample of air is saturated with benzene (vapor pressure = 100 mm Hg at 298 K) at 298K, 750mm Hgpressure. If it is isothermally compressed to one third of its initial volume, the final pressure of the system is

(1) 2250 torr

(2) 2150 torr

(3) 2050 torr

(4) 1950 torr

Concept Questions :-

Relative Lowering of Vapour Pressure/ Vapour Pressure
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Difficulty Level:

Available solutions are 1L of 0.1 M NaCl and 2L of 0.2 M CaCl2. Using only these two solutions what maximum volume of a solution can be prepared having [Cl] = 0.34M exactly. Both electrolytes are strong

(1) 2.5 L

(2) 2.4 L

(3) 2.3 L

(4) None of these

Concept Questions :-

Concentration Term and Numericals
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Difficulty Level:

Calculate the osmotic pressure of the solution prepared in the abovequestionT = 300 K, (R = 0.082 L atm mol-1K-1)

(1) 10.8 atm

(2) 12.8 atm

(3) 5.6 atm

(4) None of these

Concept Questions :-

Osmosis and Osmotic Pressure
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Difficulty Level:

Consider equimolal aqueous solutions of NaHSO4 and NaCl with ATb and Arb as their respective boiling point elevations. The value of $\underset{x\to 0}{\mathrm{lim}}\text{\hspace{0.17em}}\frac{\Delta {T}_{b}}{\Delta {T}_{b}^{\text{'}}}$ will be :

(1) 1

(2) 1.5

(3) 3.5

(4) 3

Concept Questions :-

Elevation of Boiling Point
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Difficulty Level:

The vapor pressures of benzene, toluene and a xylene are 75 Torr, 22 Torrand 10 Torr at 20°C. Which of the following is not a possible value of the vapor pressure of an equimolar binary/ternary solution of these at 20°C ? Assume all form ideal solution with each other.

(1) 48$\frac{1}{2}$

(2) 16

(3) $35\frac{2}{3}$

(4) 53$\frac{1}{2}$

Concept Questions :-

Dalton’s Law of Partial Pressure/ Henry"s law
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Difficulty Level:

3.24 g of Hg(NO3)2 (molar mass = 324) dissolved in 1000 g of water constitutes a solution having afreezing point of –0.0558°C while 21.68 g of HgC12 (molar mass = 271) in 2000 g of water constitutesa solution with a freezing point of –0.0744°C. The Kf for water is 1.86 . About the state of ionization of these two solids in water it can be inferred that:

(1) Hg(NO3)2 and HgCl2 both are completely ionized

(2) Hg(NO3)2 is fully ionized but HgCl2 is fully unionized

(3) Hg(NO3)2 and HgCl2 both are completely unionized

(4) Hg(NO3)2 is fully unionized but HgCl2 is fully ionized

Concept Questions :-

Concentration Term and Numericals
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Difficulty Level:

15 g of methyl alcohol is dissolved in 35 g of water. The weight percentage of methyl alcohol in solution is

(1) 30%

(2) 50%

(3) 70%

(4) 75%

Concept Questions :-

Concentration Term and Numericals
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Difficulty Level:

Sea water contains 5.8 × 10–3 g of dissolved oxygen per kilogram. The concentration of oxygen in parts per million is

(1) 5.8 ppm

(2) 58.5 ppm

(3) 0.58 ppm

(4) 0.05 ppm

Concept Questions :-

Concentration Term and Numericals
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Difficulty Level:

A 500 gm toothpaste sample has 0.2 g fluoride concentration. The concentration of fluoride ions in terms of ppm level is [AIIMS 1994]

(1) 250 ppm

(2) 200 ppm

(3) 400 ppm

(4) 1000 ppm

Concept Questions :-

Concentration Term and Numericals