SSC MTS - Chemical Engineering Thermodynamics 1000+ MCQ [Solved] PDF Download

1. In case of vapour compression refrigeration system, elevating the evaporator temperature (keeping the condenser temperature constant) results in
A. Enhanced COP
B. Decreased COP
C. No change in the value of COP
D. Increased or decreased COP; depending upon the type of refrigerant
Answer : A

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

3. In jet refrigerators, the refrigerating fluid is practically always
A. Water
B. Ammonia
C. Freon
D. Brine
Answer : A

4. Which one is true for a throttling process?
A. A gas may have more than one inversion temperatures
B. The inversion temperature is different for different gases
C. The inversion temperature is same for all gases
D. The inversion temperature is the temperature at which Joule-Thomson co-efficient is infinity
Answer : B

5. For a spontaneous process, free energy
A. Is zero
B. Increases
C. Decreases whereas the entropy increases
D. And entropy both decrease
Answer : C

6. Activity co-efficient is a measure of the
A. Departure from ideal solution behaviour
B. Departure of gas phase from ideal gas law
C. Vapour pressure of liquid
D. None of these
Answer : A

7. The number of degrees of freedom for a mixture of ice and water (liquid) are
A. 3
B. 2
C. 1
D. 0
Answer : C

8. During a reversible isothermal expansion of an ideal gas, the entropy change is
A. +ve
B. 0
C. -ve
D. ?
Answer : A

9. 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

10. Which of the following is not an intensive property?
A. Chemical potential
B. Surface tension
C. Heat capacity
D. None of these
Answer : C

11. Which of the following behaves most closely like an ideal gas?
A. He
B. N₂
C. O₂
D. H₂
Answer : A

12. 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

13. Entropy of the system decreases, when
A. Snow melts into water
B. A gas expands spontaneously from high pressure to low pressure
C. Water is converted into ice
D. Both (B) & (C)
Answer : D

14. The fugacity of a gas in a mixture is equal to the product of its mole fraction and its fugacity in the pure state at the total pressure of the mixture. This is
A. The statement as per Gibbs-Helmholtz
B. Called Lewis-Randall rule
C. Henry's law
D. None of these
Answer : B

15. The equation DU = Tds - PdV is applicable to infinitesimal changes occuring in
A. An open system of constant composition
B. A closed system of constant composition
C. An open system with changes in composition
D. A closed system with changes in composition
Answer : D

16. A system is said to be at equilibrium, if the entropy of the system has reached __________ value.
A. Minimum
B. Zero
C. Maximum
D. None of these
Answer : C

17. Efficiency of a Carnot engine working between temperatures T₁ and T₂ (T₁ < T) is
A. (T₂ - T₁)/T₂
B. (T₂ - T₁)/T₁
C. (T₁ - T₂)/T₂
D. (T₁ - T₂)/T₁
Answer : A

18. For a single component two phase mixture, the number of independent variable properties are
A. Two
B. One
C. Zero
D. Three
Answer : B

19. Heat is added at constant pressure in an ideal __________ cycle.
A. Stirling
B. Brayton
C. Rankine
D. Both (B) and (C)
Answer : D

20. Helmholtz free energy (A) is defined as
A. A = H - TS
B. A = E - TS
C. A = H + TS
D. None of these
Answer : B

21. Which of the following represents the Virial equation of state?
A. T = [RT/(V- b)] - [a/?T. V(V + b)]
B. PV/RT = 1 + (B/V) + (C/V²) + ……
C. n₁u₂ + ?₂?₁ = 0
D. None of these
Answer : B

22. 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

23. The free energy change for a chemical reaction is given by (where, K = equilibrium constant)
A. RT ln K
B. -RT ln K
C. -R ln K
D. T ln K
Answer : B

24. Enthalpy 'H' is defined as
A. H = E - PV
B. H = F - TS
C. H - E = PV
D. None of these
Answer : C

25. What is the number of degrees of freedom for liquid water in equilibrium with a mixture of nitrogen and water vapor?
A. 2
B. 0
C. 3
D. 1
Answer : A

26. 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

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

28. Translational kinetic energy of molecules of an ideal gas is proportional to (where, T = absolute temperature of the gas)
A. T
B. ?T
C. T²
D. 1/?T
Answer : A

29. 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

30. Pick out the wrong statement.
A. The values of (?P/?V)_T and (?²P/?V²)_T are zero for a real gas at its critical point
B. Heat transferred is equal to the change in the enthalpy of the system, for a constant pressure, non-flow, mechanically reversible process
C. Thermal efficiency of a Carnot engine depends upon the properties of the working fluid besides the source & sink temperatures
D. During a reversible adiabatic process, the entropy of a substance remains constant
Answer : C

31. 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

32. Pick out the wrong statement.
A. The net change in entropy in any reversible cycle is always zero
B. The entropy of the system as a whole in an irreversible process increases
C. The entropy of the universe tends to a maximum
D. The entropy of a substance does not remain constant during a reversible adiabatic change
Answer : D

33. The absolute entropy for all crystalline substances at absolute zero temperature is
A. Zero
B. Negative
C. More than zero
D. Indeterminate
Answer : A

34. A gas mixture of three components is brought in contact with a dispersion of an organic phase in water. The degree of freedom of the system is
A. 3
B. 4
C. 5
D. 6
Answer : A

35. 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

36. The Carnot co-efficient of performance (COP) of a domestic air conditioner compared to a household refrigerator is
A. Less
B. More
C. Same
D. Dependent on climatic conditions
Answer : A

37. 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

38. At normal boiling point, molar entropy of vaporisation is __________ Joule/K°.mole.
A. 72
B. 92
C. 142
D. 192
Answer : B

39. The internal energy of an ideal gas does not change in a reversible __________ process.
A. Isothermal
B. Adiabatic
C. Isobaric
D. Isometric
Answer : A

40. Pick out the wrong statement.
A. The chemical potential of a pure substance depends upon the temperature and pressure
B. The chemical potential of a component in a system is directly proportional to the escaping tendency of that component
C. The chemical potential of ith species (?_i) in an ideal gas mixture approaches zero as the pressure or mole fraction (x_i) tends to be zero at constant temperature
D. The chemical potential of species 'i' in the mixture (?_i) is mathematically represented as,?_i = ?(nG)/?ni]_T,P,nj where, n, n_i and n_j respectively denote the total number of moles, moles of i^th species and all mole numbers except ith species. 'G' is Gibbs molar free energy
Answer : C

41. Which of the following is not an equation of state?
A. Bertholet equation
B. Clausius-Clapeyron equation
C. Beattie-Bridgeman equation
D. None of these
Answer : B

42. A refrigerator works on the principle of __________ law of thermodynamics.
A. Zeroth
B. First
C. Second
D. Third
Answer : C

43. At equilibrium condition, the chemical potential of a material in different phases in contact with each other is equal. The chemical potential for a real gas (?) is given by (where, ? = standard chemical potential at unit fugacity (f° = 1 atm.) and the gas behaves ideally.)
A. ?° + RT ln f
B. ?°+ R ln f
C. ?° + T ln f
D. ?° + R/T ln f
Answer : A

44. The temperature at the eutectic point of the system is the __________ temperature that can be attained in the system.
A. Lowest
B. Highest
C. Average
D. None of these
Answer : A

45. Pick out the wrong statement.
A. Enthalpies of all elements in their standard states are assumed to be zero
B. Combustion reactions are never endothermic in nature
C. Heat of reaction at constant volume is equal to the change in internal energy
D. Clausius-Clapeyron equation is not applicable to melting process
Answer : D

46. At triple point (for one component system), vapour pressure of solid as compared to that of liquid will be
A. More
B. Less
C. Same
D. More or less; depending on the system
Answer : C

47. The expression for entropy change given by, ?S = nR ln (V₂/V₁) + nC_v ln (T₂/T₁) is valid for
A. Reversible isothermal volume change
B. Heating of a substance
C. Cooling of a substance
D. Simultaneous heating and expansion of an ideal gas
Answer : D

48. Fugacity co-efficient of a substance is the ratio of its fugacity to
A. Mole fraction
B. Activity
C. Pressure
D. Activity co-efficient
Answer : C

49. 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

50. Solubility of a substance which dissolves with an increase in volume and liberation of heat will be favoured by the
A. Low pressure and high temperature
B. Low pressure and low temperature
C. High pressure and low temperature
D. High pressure and high temperature
Answer : B