Chemical Engineering Thermodynamics MCQ Solved Paper for ISRO Recruitment

1. If the pressure on 100 c.c. of air is halved, then its volume (at the same temperature) would be __________ c.c.
A. 100
B. 50
C. 205
D. 200
Answer : D

2. If atmospheric temperature and dew point are nearly equal, then the relative humidity is
A. Zero
B. 50%
C. Almost 100%
D. unpredictable
Answer : C

3. In the reaction; N₂ + O₂ ? 2NO, increasing the pressure will result in
A. Shifting the equilibrium towards right
B. Shifting the equilibrium towards left
C. No change in equilibrium condition
D. None of these
Answer : C

4. For a thermodynamic system containing 'x' chemical species, the maximum number of phases that can co-exist at equilibrium is
A. x
B. x + 1
C. x + 2
D. x + 3
Answer : C

5. First law of thermodynamics is mathematically stated as
A. dQ = dE + dW
B. dQ = dE - dW
C. dE = dQ + dW
D. dW = dQ + dE
Answer : A

6. Gibbs-Duhem equation
A. States that n₁d?₁ + n₂d?₂ + ....n_jd?_j = 0, for a system of definite composition at constant temperature and pressure
B. Applies only to binary systems
C. Finds no application in gas-liquid equilibria involved in distillation
D. None of these
Answer : A

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

8. A solid is transformed into vapour without going to the liquid phase at
A. Triple point
B. Boiling point
C. Below triple point
D. Always
Answer : A

9. Free energy
A. Decreases in all spontaneous (or irreversible) processes
B. Change during a spontaneous process has a negative value
C. Remains unchanged in reversible processes carried at constant temperature and pressure
D. All (A), (B) and (C)
Answer : D

10. Heat of reaction at constant volume is identified with __________ change.
A. Enthalpy
B. Internal energy
C. Either (A) or (B)
D. Neither (A) nor (B)
Answer : B

11. The reaction A (l) ? R(g) is allowed to reach equilibrium conditions in an autoclave. At equilibrium, there are two phases, one a pure liquid phase of A and the other a vapor phase of A, R and S. Initially A alone is present. The numbers of degrees of freedom are:
A. 1
B. 2
C. 3
D. 0
Answer : B

12. 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

13. The compressibility factor for an ideal gas is 1. Its value for any other real gas is
A. 1
B. < 1
C. > 1
D. Either (B) or (C), depends on the nature of the gas
Answer : D

14. All gases except __________ shows a cooling effect during throttling process at atmospheric temperature and pressure.
A. Oxygen
B. Nitrogen
C. Air
D. Hydrogen
Answer : D

15. With increase in temperature, the internal energy of a substance
A. Increases
B. Decreases
C. Remains unchanged
D. May increase or decrease; depends on the substance
Answer : A

16. Co-efficient of Performance (COP) of a refrigerator is the ratio of the
A. Work required to refrigeration obtained
B. Refrigeration obtained to the work required
C. Lower to higher temperature
D. Higher to lower temperature
Answer : B

17. For a cyclic process, a fixed ratio between heat and work
A. Always exists
B. May exist
C. Never exists
D. Is difficult to predict
Answer : A

18. 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

19. Which of the following units is not present in both the vapor compression refrigeration system and absorption refrigeration system?
A. Expansion valve
B. Condenser
C. Refrigerator
D. Compressor
Answer : D

20. The equation Tds = dE - PdV applies to
A. Single phase fluid of varying composition
B. Single phase fluid of constant composition
C. Open as well as closed systems
D. Both (B) and (C)
Answer : D

21. A refrigeration cycle is the same as a __________ cycle,
A. Turbine
B. Heat engine
C. Reversed heat engine
D. None of these
Answer : C

22. High __________ is an undesirable property for a good refrigerant.
A. Specific heat
B. Latent heat of vaporisation
C. Viscosity
D. Specific vapor volume
Answer : C

23. The expression for entropy change, ?S = n C_p . ln (T₂/T₁), is valid for the __________ of a substance.
A. Simultaneous pressure & temperature change
B. Heating
C. Cooling
D. Both (B) and (C)
Answer : D

24. y = specific heat ratio of an ideal gas is equal to
A. C_p/C_v
B. C_p/(C_P-R)
C. 1 + (R/C_V)
D. All (A), (B) and (C)
Answer : D

25. The unit of fugacity is the same as that of the
A. Pressure
B. Temperature
C. Volume
D. Molar concentration
Answer : A

26. During the phase transition, __________ changes.
A. Pressure
B. Volume
C. Temperature
D. All (A), (B) and (C)
Answer : B

27. Pick out the undesirable property for a good refrigerant.
A. High thermal conductivity
B. Low freezing point
C. Large latent heat of vaporisation
D. High viscosity
Answer : D

28. For an isothermal process, the internal energy of a gas
A. Increases
B. Decreases
C. Remains unchanged
D. Data insufficient, can't be predicted
Answer : C

29. A/an __________ system is exemplified by a vessel containing a volatile liquid in contact with its vapor.
A. Isolated
B. Closed
C. Open
D. None of these
Answer : C

30. If the molar heat capacities (C_p or C_v) of the reactants and products of a chemical reaction are identical, then, with the increase in temperature, the heat of reaction will
A. Increase
B. Decrease
C. Remain unaltered
D. Increase or decrease; depends on the particular reaction
Answer : C

31. The equation relating E, P, V and T which is true for all substances under all conditions is given by (?E/?V)_T = T(?P/?T)_H - P. This equation is called the
A. Maxwell's equation
B. Thermodynamic equation of state
C. Equation of state
D. Redlich-Kwong equation of state
Answer : B

32. Consider the reaction, C + O₂ ? CO₂; ?H = - 94 kcal. What will be the value of ?H for the reaction CO₂ ? C + O₂?
A. -94 kcal
B. +94 kcal
C. > 94 kcal
D. < -94 kcal
Answer : B

33. The variation of heat of reaction with temperature at constant pressure is given by the __________ law.
A. Kelvin's
B. Antoines
C. Kirchoffs
D. None of these
Answer : C

34. Fugacity of a component in an ideal gas mixture is equal to the partial pressure of that component in the mixture. The fugacity of each component in a stable homogeneous solution at constant pressure and temperature __________ as its mole fraction increases.
A. Decreases
B. Decreases exponentially
C. Increases
D. Remain constant
Answer : C

35. Pick out the wrong statement.
A. Trouton's ratio of non-polar liquids is calculated using Kistyakowsky equation
B. Thermal efficiency of a Carnot engine is always less than 1
C. An equation relating pressure, volume and temperature of a gas is called ideal gas equation
D. None of these
Answer : C

36. If the internal energy of an ideal gas decreases by the same amount as the work done by the system, then the
A. Process must be isobaric
B. Temperature must decrease
C. Process must be adiabatic
D. Both (B) and (C)
Answer : D

37. The third law of thermodynamics states that the
A. Heat capacity of a crystalline solid is zero at absolute zero temperature
B. Heat transfer from low temperature to high temperature source is not possible without external work
C. Gases having same reduced properties behaves similarly
D. None of these
Answer : A

38. Entropy change in case of reversible adiabatic process is
A. Minimum
B. Zero
C. Maximum
D. Indeterminate
Answer : B

39. In case of the decomposition of hydroiodic acid (2HI ? H₂ + I₂), addition of H₂ (at equilibrium condition) will
A. Increase the partial pressure of I₂
B. Decrease the partial pressure of HI
C. Diminish the degree of dissociation of HI
D. None of these
Answer : C

40. Pressure-enthalpy chart is useful in refrigeration. The change in internal energy of an ideal fluid used in ideal refrigeration cycle is
A. Positive
B. Negative
C. Zero
D. Infinity
Answer : C

41. Dry ice is
A. Moisture free ice
B. Solid helium
C. Solid carbon dioxide
D. None of these
Answer : C

42. When liquid and vapour phase of multi-component system are in equilibrium (at a given temperature and pressure), then chemical potential of each component is
A. Same in both the phases
B. Zero in both the phases
C. More in vapour phase
D. More in liquid phase
Anwer : A

43. As the temperature is lowered towards the absolute zero, the value of ?(?F)/?T, then approaches
A. Unity
B. Zero
C. That of the heat of reaction
D. Infinity
Answer : B

44. COP of a refrigerator drawing 1 kW of power per ton of refrigeration is about
A. 0.5
B. 3.5
C. 4.5
D. 8.5
Answer : B

45. For a constant volume process
A. dE = C_pdT
B. dE = C_vdT
C. dQ = dE + pdV
D. dW = pdV
Answer : B

46. An ideal monatomic gas is taken round the cycle ABCDA as shown below in the P-V diagram. The work done during the cycle is

A. PV
B. 2PV
C. PV/2
D. 0
Answer : A

47. When a gas is expanded from high pressure region to low pressure region; temperature change occurs. This phenomenon is related to the
A. Gibbs-Duhem equation
B. Gibbs-Helmholtz equation
C. Third law of thermodynamics
D. Joule-Thomson effect
Answer : D

48. Critical compressibility factor for all substances
A. Are more or less constant (vary from 0.2 to 0.3)
B. Vary as square of the absolute temperature
C. Vary as square of the absolute pressure
D. None of these
Answer : A

49. Pick out the correct statement.
A. A real gas on expansion in vacuum gets heated up
B. An ideal gas on expansion in vacuum gets cooled
C. An ideal gas on expansion in vacuum gets heated up
D. A real gas on expansion in vacuum cools down whereas ideal gas remains unaffected
Answer : D

50. Refrigeration cycle
A. Violates second law of thermodynamics
B. Involves transfer of heat from low temperature to high temperature
C. Both (A) and (B)
D. Neither (A) nor (B)
Answer : B