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Solutions · Question 21

NEET 2016 (Phase 1)MCQMedium📈 Topic in 0% papers+4−1
1

Which of the following statements about the composition of the vapour over an ideal 1 : 1 molar mixture of benzene and toluene is correct? Assume that the temperature is constant at 25 . (Given, vapour pressure data at 25 , benzene = 12.8 kPa, toluene = 3.85 kPa)

  1. The vapour will contain equal amounts of benzene and toluene.
  2. Not enough information is given to make a prediction.
  3. The vapour will contain a higher percentage of benzene.
  4. The vapour will contain a higher percentage of toluene

Answer

(3) The vapour will contain a higher percentage of benzene.

Solution

For a 1 : 1 molar mixture, xB = xT = 0.5.

By Raoult's law:

pB = xB pB = 0.5 12.8 = 6.4 kPa

pT = xT pT = 0.5 3.85 = 1.925 kPa

Mole fraction of benzene in vapour:

yB = pBpB + pT = 6.48.325 = 0.77

∴ The vapour contains about 77% benzene, i.e. it is richer in the more volatile component, benzene.

Answer: (3)

NEET 2016 (Phase 1)

Keep practising — Solutions

2

At 100 the vapour pressure of a solution of 6.5 g of a solute in 100 g water is 732 mm. If Kb = 0.52, the boiling point of this solution will be

  1. 102
  2. 103
  3. 101
  4. 100
NEET 2016 (Phase 1)
3

The van't Hoff factor (i) for a dilute aqueous solution of the strong electrolyte barium hydroxide is

  1. 0
  2. 1
  3. 2
  4. 3
NEET 2016 (Phase 2)
4

Which one of the following is incorrect for ideal solution?

  1. Hmix = 0
  2. Umix = 0
  3. P = Pobs - Pcalculated by Raoult's law = 0
  4. Gmix = 0
NEET 2016 (Phase 2)
5

What is the mole fraction of the solute in a 1.00 m aqueous solution?

  1. 1.770
  2. 0.0354
  3. 0.0177
  4. 0.177
AIPMT 2015
6

The boiling point of 0.2 mol kg-1 solution of X in water is greater than equimolal solution of Y in water. Which one of the following statements is true in this case?

  1. Molecular mass of X is less than the molecular mass of Y.
  2. Y is undergoing dissociation in water while X undergoes no change.
  3. X is undergoing dissociation in water.
  4. Molecular mass of X is greater than the molecular mass of Y.
AIPMT 2015 (Cancelled)
7

Which one of the following electrolytes has the same value of van't Hoff factor (i) as that of Al2(SO4)3 (if all are 100% ionised)?

  1. Al(NO3)3
  2. K4[Fe(CN)6]
  3. K2SO4
  4. K3[Fe(CN)6]
AIPMT 2015 (Cancelled)
8

Which of them is not equal to zero for an ideal solution?

  1. Vmix
  2. P = Pobserved - PRaoult
  3. Hmix
  4. Smix
AIPMT 2015 (Cancelled)
9

Of the following 0.10 m aqueous solutions, which one will exhibit the largest freezing point depression?

  1. KCl
  2. C6H12O6
  3. Al2(SO4)3
  4. K2SO4
AIPMT 2014
10

Which condition is not satisfied by an ideal solution?

  1. mixV = 0
  2. mixS = 0
  3. Obeyance to Raoult's Law
  4. mixH = 0
NEET 2013 (Karnataka)
11

Vapour pressure of chloroform (CHCl3) and dichloromethane (CH2Cl2) at 25 are 200 mm Hg and 41.5 mm Hg respectively. Vapour pressure of the solution obtained by mixing 25.5 g of CHCl3 and 40 g of CH2Cl2 at the same temperature will be (Molecular mass of CHCl3 = 119.5 u and molecular mass of CH2Cl2 = 85 u)

  1. 173.9 mm Hg
  2. 615.0 mm Hg
  3. 90.6 mm Hg
  4. 285.5 mm Hg
AIPMT 2012 (Mains)

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