Stoichiometry

61. A vapor that exists above its critical temperature is termed as a _________ vapor.

  1. Saturated
  2. Unsaturated
  3. Gaseous
  4. Sub-cooled

Correct answer: (C)
Gaseous

62. A vapor whose partial pressure is less than its equilibrium vapor pressure is called a _________ vapor.

  1. Saturated
  2. Supersaturated
  3. Superheated
  4. None of these

Correct answer: (C)
Superheated

63. A vapor whose partial pressure is less than its equilibrium vapor pressure is called the _________ vapor.

  1. Saturated
  2. Superheated
  3. Unsaturated
  4. Dry gaseous

Correct answer: (B)
Superheated

64. 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

  1. x1/x2
  2. x2/x1
  3. 1 - (x1/x2)
  4. 1/x2

Correct answer: (A)
x1/x2

65. A vessel of volume 1000 m3 contains air which is saturated with water vapour. The total pressure and temperature are 100 kPa and 20°C respectively. Assuming that the vapour pressure of water at 20°C is 2.34 kPa, the amount of water vapour (in kg) in the vessel is approximately

  1. 17
  2. 20
  3. 25
  4. 34

Correct answer: (A)
17

66. According to Raoult's law, "The vapor pressure exerted by component in a solution is proportional to the mole fraction of that component." Raoult's law is not applicable under the following assumption/condition.

  1. No component is concentrated at the surface of the solution
  2. The component molecules are non polar and are of almost equal size
  3. In the formation of solution, chemical combination/molecular association between unlike molecules takes place
  4. The attractive forces between like and unlike molecules are almost equal

Correct answer: (C)
In the formation of solution, chemical combination/molecular association between unlike molecules takes place

67. According to the kinetic theory, the thermal conductivity of a monatomic gas is proportional to

  1. T
  2. T0.5
  3. T1.5
  4. T2

Correct answer: (B)
T0.5

68. Acidity or alkanity of a solution is expressed by its pH value, which is defined as (where, [H+] = hydrogen ion concentration in the solution).

  1. log (1/H+)
  2. - log (1/H+)
  3. 1/log H+
  4. None of these

Correct answer: (A)
log (1/H+)

69. Addition of a non-volatile solute to a pure solvent

  1. Increases its freezing point
  2. Increases its boiling point
  3. Decreases its freezing point
  4. Both (B) and (C)

Correct answer: (D)
Both (B) and (C)

70. Addition of a non-volatile solute to a solvent produces a _________ in its solvent.

  1. Freezing point elevation
  2. Boiling point depression
  3. Vapor pressure lowering
  4. All (A), (B) & (C)

Correct answer: (C)
Vapor pressure lowering

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