Chemical Engineering Thermodynamics

71. At normal boiling point, molar entropy of vaporisation is _________ Joule/K°.mole.

1. 72
2. 92
3. 142
4. 192

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72. At the absolute zero temperature, the entropy of every perfectly crystalline substance becomes zero. This follows from the

1. Third law of thermodynamics
2. Second law of thermodynamics
3. Nernst heat theorem
4. Maxwell's relations

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73. At the critical point of a substance

1. The surface tension vanishes
2. Liquid and vapour have the same density
3. There is no distinction between liquid and vapour phases
4. All (A), (B) and (C)

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74. At triple point (for one component system), vapour pressure of solid as compared to that of liquid will be

1. More
2. Less
3. Same
4. More or less; depending on the system

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75. Boiling of liquid is accompanied with increase in the

1. Vapor pressure
2. Specific Gibbs free energy
3. Specific entropy
4. All (A), (B) and (C)

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76. Boyle's law for gases states that

1. P ∝ 1/V, when temperature is constant
2. P ∝ 1/V, when temperature & mass of the gas remain constant
3. P ∝ V, at constant temperature & mass of the gas
4. P/V = constant, for any gas

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77. C_p of a gas at its critical temperature and pressure

1. Becomes zero
2. Becomes infinity
3. Equals 1 kcal/kmol °K
4. Equals 0.24 kcal/kmol °K

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78. Change of heat content when one mole of compound is burnt in oxygen at constant pressure is called the

1. Calorific value
2. Heat of reaction
3. Heat of combustion
4. Heat of formation

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79. Change of state namely evaporation condensation, freezing and melting is an _________ process.

1. Isothermal
2. Adiabatic
3. Isobaric
4. Isochoric

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80. Charles' law for gases states that

1. V/T = Constant
2. V ∝ 1/T
3. V ∝ 1/P
4. PV/T = Constant

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