Chemical Engineering Thermodynamics

41. A system is said to be isopiestic, if there is no _________ change.

  1. Temperature
  2. Pressure
  3. Volume
  4. None of these

Correct answer: (B)
Pressure

42. A system undergoes a change from a given initial state to a given final state either by an irreversible process or by a reversible process, then (where, Δ S1 and Δ SR are the entropy changes of the system for the irreversible and reversible processes respectively)

  1. Δ S1 is always < Δ SR
  2. Δ S1 is sometimes > Δ SR
  3. Δ S1 is always > Δ SR
  4. Δ S1 is always = Δ SR

Correct answer: (C)
Δ S1 is always > Δ SR

43. A two stage compressor is used to compress an ideal gas. The gas is cooled to the initial temperature after each stage. The intermediate pressure for the minimum total work requirement should be equal to the _________ mean of P1 and P2.(where, P1 and P2 are initial and final pressures respectively)

  1. Logarithmic
  2. Arithmetic
  3. Geometric
  4. Harmonic

Correct answer: (C)
Geometric

44. A/an _________ system is exemplified by a vessel containing a volatile liquid in contact with its vapor.

  1. Isolated
  2. Closed
  3. Open
  4. None of these

Correct answer: (C)
Open

45. Absolute zero temperature signifies the

  1. Minimum temperature attainable
  2. Temperature of the heat reservoir to which a Carnot engine rejects all the heat that is taken in
  3. Temperature of the heat reservoir to which a Carnot engine rejects no heat
  4. None of these

Correct answer: (C)
Temperature of the heat reservoir to which a Carnot engine rejects no heat

46. Absorption/evolution of heat during conversion of a substance from one allotropic form to another is termed as the heat of

  1. Sublimation
  2. Fusion
  3. Transition
  4. Vaporisation

Correct answer: (C)
Transition

47. Activity co-efficient is a measure of the

  1. Departure from ideal solution behaviour
  2. Departure of gas phase from ideal gas law
  3. Vapour pressure of liquid
  4. None of these

Correct answer: (A)
Departure from ideal solution behaviour

48. Adiabatic compression of a saturated water vapour makes it

  1. Supersaturated
  2. Superheated
  3. Both (A) and (B)
  4. Neither (A) nor (B)

Correct answer: (B)
Superheated

49. After throttling, gas temperature

  1. Decreases
  2. Increases
  3. Remain same
  4. May increase or decrease; depends on the nature of the gas

Correct answer: (A)
Decreases

50. Air enters an adiabatic compressor at 300K. The exit temperature for a compression ratio of 3, assuming air to be an ideal gas (Y = Cp/Cv = 7/5) and the process to be reversible, is

  1. 300 × (32/7)
  2. 300 × (33/7)
  3. 300 × (333/7)
  4. 300 × (35/7)

Correct answer: (A)
300 × (32/7)

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