1000+ Chemical Engineering Thermodynamics Multiple Choice Question Answer [Solved]

1. __________ decreases during adiabatic throttling of a perfect gas.
A. Entropy
B. Temperature
C. Enthalpy
D. Pressure
Answer : D

2. Pick out the wrong statement pertaining to the decomposition of PCl₅ represented by, PCl₅ ? PCl₃ + Cl₂.Degree of dissociation of PCl₅ will
A. Decrease on addition of Cl₂
B. Increase on addition of an inert gas at constant pressure
C. Decrease on increasing the pressure of the system
D. None of these
Answer : D

3. The work done in an adiabatic change in a particular gas depends upon changes in the __________ only.
A. Temperature
B. Specific heat
C. Volume
D. Pressure
Answer : A

4. As the temperature is lowered towards the absolute zero, the value of the quantity (??F/?T) approaches
A. Zero
B. Unity
C. Infinity
D. None of these
Answer : A

5. Internal energy of an element at 1 atm and 25° C is __________ kcal/kg.mole.
A. 0
B. 273
C. 25
D. None of these
Answer : A

6. Pick out the wrong statement.
A. A refrigeration cycle violates the second law of thermodynamics
B. Refrigeration cycle is normally represented by a temperature vs. entropy plot
C. In a refrigerator, work required decreases as the temperature of the refrigerator and the temperature at which heat is rejected increases
D. One ton of refrigeration is equivalent to the rate of heat absorption equal to 3.53 kW
Answer : A

7. The kinetic energy of gas molecule is zero at
A. 0°C
B. 273°C
C. 100°C
D. -273°C
Answer : D

8. The necessary and sufficient condition for equilibrium between two phases is
A. The concentration of each component should be same in the two phases
B. The temperature of each phase should be same
C. The pressure should be same in the two phases
D. The chemical potential of each component should be same in the two phases
Answer : D

9. The main feature of Carnot refrigeration cycle is that, it
A. Does not need the addition of external work for its functioning
B. Transfers heat from high temperature to low temperature
C. Accomplishes the reverse effect of the heat engine
D. None of these
Answer : C

10. A chemical reaction will occur spontaneously at constant pressure and temperature, if the free energy is
A. Zero
B. Positive
C. Negative
D. None of these
Answer : C

11. Joule-Thomson experiment is
A. Isobaric
B. Adiabatic
C. Isenthalpic
D. Both (B) & (C)
Answer : D

12. The temperature at which both liquid and gas phases are identical, is called the __________ point.
A. Critical
B. Triple
C. Freezing
D. Boiling
Answer : A

13. For water at 300°C, it has a vapour pressure 8592.7 kPa and fugacity 6738.9 kPa Under these conditions, one mole of water in liquid phase has a volume of 25.28 cm3 and that in vapour phase in 391.1 cm3.Fugacity of water (in kPa) at 9000 kPa will be
A. 6738.9
B. 6753.5
C. 7058.3
D. 9000
Answer : B

14. Heating of water under atmospheric pressure is an __________ process.
A. Isochoric
B. Isobaric
C. Adiabatic
D. Isothermal
Answer : B

15. Critical solution temperature (or the consolute temperature) for partially miscible liquids (e.g., phenol-water) is the minimum temperature at which
A. A homogeneous solution (say of phenol water) is formed
B. Mutual solubility of the two liquids shows a decreasing trend
C. Two liquids are completely separated into two layers
D. None of these
Answer : A

16. What is the number of degree of freedom for a system of two miscible non-reacting species in vapor-liquid equilibrium forming an azeotrope?
A. 0
B. 2
C. 1
D. 3
Answer : C

17. First law of thermodynamics deals with the
A. Direction of energy transfer
B. Reversible processes only
C. Irreversible processes only
D. None of these
Answer : A

18. Pick out the wrong statement.
A. At constant pressure, solubility of a gas in a liquid diminishes with rise in temperature
B. Normally, the gases which are easily liquefied are more soluble in common solvents
C. The gases which are capable of forming ions in aqueous solution are much more soluble in water than in other solvents
D. At constant pressure, solubility of a gas in a liquid increases with rise in temperature
Answer : A

19. A solid metallic block weighing 5 kg has an initial temperature of 500°C. 40 kg of water initially at 25°C is contained in a perfectly insulated tank. The metallic block is brought into contact with water. Both of them come to equilibrium. Specific heat of block material is 0.4 kJ.kg^-1. K^-1. Ignoring the effect of expansion and contraction and also the heat capacity to tank, the total entropy change in kJ.kg^-1, K^-1 is
A. -1.87
B. 0
C. 1.26
D. 3.91
Answer : B

20. All gases above its inversion temperature, in a throttling process will show
A. A heating effect
B. No change in temperature
C. A cooling effect
D. Either (A) or (C)
Answer : A

21. A Carnot cycle consists of the following steps:
A. Two isothermal and two isentropic
B. Two isobaric and two isothermal
C. Two isochoric and two isobaric
D. Two isothermals and two isochoric
Answer : A

22. At constant temperature and pressure, for one mole of a pure substance, the ratio of the free energy to the chemical potential is
A. Zero
B. One
C. Infinity
D. Negative
Answer : B

23. For a constant volume process __________ by the system is used only to increase the internal energy.
A. Heat absorbed
B. Work done
C. Both (A) & (B)
D. Neither (A) nor (B)
Answer : A

24. __________ functions are exemplified by heat and work.
A. Path
B. Point
C. State
D. None of these
Answer : A

25. When a gas in a vessel expands, its internal energy decreases. The process involved is
A. Reversible
B. Irreversible
C. Isothermal
D. Adiabatic
Answer : A

26. Pick out the correct statement:
A. In an isothermal system, irreversible work is more than reversible work
B. Under reversible conditions, the adiabatic work is less than isothermal work
C. Heat, work, enthalpy and entropy are all 'state functions'
D. Matter and energy cannot be exchanged with the surroundings in a closed system
Answer : B

27. In the equation, PVn = Constant, if the value of n = 0, then it represents a reversible __________ process.
A. Isobaric
B. Isothermal
C. Isentropic
D. Isometric
Answer : A

28. The change in __________ is equal to the reversible work for compression in steady state flow process under isothermal condition.
A. Internal energy
B. Enthalpy
C. Gibbs free energy
D. Helmholtz free energy
Answer : C

29. Equation which relates pressure, volume and temperature of a gas is called the
A. Equation of state
B. Gibbs Duhem equation
C. Ideal gas equation
D. None of these
Answer : A

30. Claude gas liquefaction process employs cooling
A. At constant pressure
B. By throttling
C. By expansion in an engine
D. None of these
Answer : C

31. The compressibility factor of a gas is given by (where, V₁ = actual volume of the gas V₂ = gas volume predicted by ideal gas law)
A. V₁/V₂
B. V₂/V₁
C. V₁ - V₂
D. V₁.V₂
Answer : A

32. Which of the following equations is obtained on combining 1st and 2nd law of thermodynamics, for a system of constant mass?
A. dE = Tds - PdV
B. dQ = C_vdT + PdV
C. dQ = C_pdT + Vdp
D. Tds = dE - PdV
Answer : A

33. 4 kg moles of an ideal gas expands in vacuum spontaneously. The work done is
A. 4 J
B. ?
C. 0
D. 8 J
Answer : C

34. Joule-Thomson Co-efficient at any point on the inversion curve is
A. ?
B. +ve
C. 0
D. -ve
Answer : C

35. Change of state namely evaporation condensation, freezing and melting is an __________ process.
A. Isothermal
B. Adiabatic
C. Isobaric
D. Isochoric
Answer : A

36. Charles' law for gases states that
A. V/T = Constant
B. V ? 1/T
C. V ? 1/P
D. PV/T = Constant
Answer : A

37. At a given temperature, the volume of a gas dissolved in a solvent __________ with increase in pressure.
A. Increases
B. Decreases
C. Remains unchanged
D. May increase or decrease; depends on the gas
Answer : C

38. Heat evolved/absorbed during conversion of a substance from one allotropic form to another is termed as the heat of
A. Fusion
B. Vaporisation
C. Transition
D. None of these
Answer : C

39. In case of steady flow compression polytropic process (PVⁿ = constant), the work done on air is the lowest, when
A. n = y = 1.4
B. n = 0
C. n = 1
D. n = 1.66
Answer : C

40. For any system, what is the minimum number of degrees of freedom?
A. 0
B. 1
C. 2
D. 3
Answer : A

41. With increase in compression ratio, the efficiency of the otto engine
A. Increases
B. Decreases
C. Remain constant
D. Increases linearly
Answer : A

42. Specific heat of a gas for a reversible adiabatic process is
A. Negative
B. Zero
C. Infinity
D. None of these
Answer : B

43. __________ increases with increase in pressure.
A. The melting point of wax
B. The boiling point of a liquid
C. Both (A) and (B)
D. Neither (A) nor (B)
Answer : C

44. The ratio of equilibrium constants (Kp2/Kp1) at two different temperatures is given by
A. (R/?H) (1/T₁ - 1/T₂)
B. (?H/R) (1/T₁ - 1/T₂)
C. (?H/R) (1/T₂ - 1/T₁)
D. (1/R) (1/T₁ - 1/T₂)
Answer : B

45. Free energy change at equilibrium is
A. Zero
B. Positive
C. Negative
D. Indeterminate
Answer : A

46. The first law of thermodynamics is a restatement of the law of conservation of
A. Mass
B. Energy
C. Momentum
D. None of these
Answer : B

47. A reasonably general expression for vapourliquid phase equilibrium at low to moderate pressure is ?_i y_i P = Y_i x_if_i° where, ? is a vapor fugacity component, Y_i is the liquid activity co-efficient and f_i° is the fugacity of the pure component i. the K_i value (Y_i = K_i x_i) is therefore, in general a function of
A. Temperature only
B. Temperature and pressure only
C. Temperature, pressure and liquid composition x_i only
D. Temperature, pressure, liquid composition x_i and vapour composition yi
Answer : C

48. The principle applied in liquefaction of gases is
A. Adiabatic expansion
B. Joule-Thomson effect
C. Both (A) and (B)
D. Neither (A) nor (B)
Answer : C

49. Specific __________ does not change during phase change at constant temperature and pressure.
A. Entropy
B. Gibbs energy
C. Internal energy
D. Enthalpy
Answer : B

50. Which of the following is not an intensive property?
A. Volume
B. Density
C. Temperature
D. Pressure
Answer : A