1000+ Chemical Engineering Thermodynamics MCQ for JEE Main [Solved]

1. For an ideal solution, the value of activity co-efficient is
A. 0
B. 1
C. < 1
D. > 1
Answer : B

2. The expression, nC_v(T₂ - T₁), is for the __________ of an ideal gas.
A. Work done under adiabatic condition
B. Co-efficient of thermal expansion
C. Compressibility
D. None of these
Answer : A

3. If an ideal solution is formed by mixing two pure liquids in any proportion, then the __________ of mixing is zero
A. Enthalpy
B. Volume
C. Both 'a' & 'b'
D. Neither 'a' nor 'b'
Answer : C

4. There is a change in __________ during the phase transition.
A. Volume
B. Pressure
C. Temperature
D. All a, b & c
Answer : A

5. 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

6. A gas performs the maximum work, when it expands
A. Non-uniformly
B. Adiabatically
C. Isobarically
D. Isothermally
Answer : C

7. 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

8. For an ideal liquid solution, which of the following is unity?
A. Activity
B. Fugacity
C. Activity co-efficient
D. Fugacity co-efficient
Answer : C

9. 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

10. 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

11. Sublimation temperature of dry ice (solid CO₂) is __________ °C.
A. -273
B. 0
C. -78
D. 5
Answer : C

12. Filling of gas from a high pressure cylinder into small bottles is an example of a/an __________ process.
A. Equilibrium
B. Adiabatic
C. Steady
D. Unsteady
Answer : D

13. The standard state of a gas (at a given temperature) is the state in which fugacity is equal to
A. Unity
B. Activity
C. Both (A) & (B)
D. Neither (A) nor (B)
Answer : C

14. 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

15. In the equation PVⁿ = constant, if the value of n = y = C_p/C_v, then it represents a reversible __________ process.
A. Isothermal
B. Adiabatic
C. Isentropic
D. Polytropic
Answer : C

16. The theoretical minimum work required to separate one mole of a liquid mixture at 1 atm, containing 50 mole % each of n- heptane and noctane into pure compounds each at 1 atm is
A. -2 RT ln 0.5
B. -RT ln 0.5
C. 0.5 RT
D. 2 RT
Answer : B

17. __________ Equation predicts the activity coefficient from experimental data.
A. Lewis-Randall
B. Margules
C. Van Laar
D. Both (B) & (C)
Answer : D

18. The expression, nRT ln(P₁/P₂), is for the __________of an ideal gas.
A. Compressibility
B. Work done under adiabatic condition
C. Work done under isothermal condition
D. Co-efficient of thermal expansion
Answer : C

19. The point at which all the three (solid, liquid and gas) phases co-exist, is known as the __________ point.
A. Freezing
B. Triple
C. Boiling
D. Boyle
Answer : B

20. Pick out the correct statement.
A. Compression ratio of an Otto engine is comparatively higher than a diesel engine
B. Efficiency of an Otto engine is higher than that of a diesel engine for the same compression ratio
C. Otto engine efficiency decreases with the rise in compression ratio, due to decrease in work produced per quantity of heat
D. Diesel engine normally operates at lower compression ratio than an Otto engine for an equal output of work
Answer : B

21. A thermodynamic system is taken from state A to B along ACB and is brought back to A along BDA as shown below in the P-V diagram. The net work done during the complete cycle is given by the area covered by

A. P₁ACBP₂P₁
B. ACBB¹A¹A
C. ACBDA
D. ADBB¹A¹A
Answer : C

22. C_p of a gas at its critical temperature and pressure
A. Becomes zero
B. Becomes infinity
C. Equals 1 kcal/kmol °K
D. Equals 0.24 kcal/kmol °K
Answer : B

23. Henry's law is closely obeyed by a gas, when its __________ is extremely high.
A. Pressure
B. Solubility
C. Temperature
D. None of these
Answer : D

24. Heat pump
A. Accomplishes only space heating in winter
B. Accomplishes only space cooling in summer
C. Accomplishes both (A) and (B)
D. Works on Carnot cycle
Answer : C

25. In a turbine, the fluid expands almost
A. Isothermally
B. Isobarically
C. Adiabatically
D. None of these
Answer : C

26. In an ideal solution, the activity of a component equals its
A. Mole fraction
B. Fugacity at the same temperature and pressure
C. Partial pressure
D. None of these
Answer : A

27. If the vapour pressure at two temperatures of a solid phase in equilibrium with its liquid phase are known, then the latent heat of fusion can be calculated by the
A. Maxwell's equation
B. Clausius-Clapeyron Equation
C. Van Laar equation
D. Nernst Heat Theorem
Answer : B

28. 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

29. Gibbs phase rule finds application, when heat transfer occurs by
A. Conduction
B. Convection
C. Radiation
D. Condensation
Answer : D

30. The second law of thermodynamics states that
A. The energy change of a system undergoing any reversible process is zero
B. It is not possible to transfer heat from a lower temperature to a higher temperature
C. The total energy of system and surrounding remains the same
D. None of the above
Answer : D

31. Measurement of thermodynamic property of temperature is facilitated by __________ law of thermodynamics.
A. 1st
B. Zeroth
C. 3rd
D. None of these
Answer : B

32. Two substances are in equilibrium in a reversible chemical reaction. If the concentration of each substance is doubled, then the value of the equilibrium constant will be
A. Same
B. Doubled
C. Halved
D. One fourth of its original value
Answer : A

33. The unit of equilibrium constant of a chemical reaction is the same as that of
A. Molar concentration
B. Temperature
C. Internal energy
D. None of these
Answer : D

34. With increase in reduced temperature, the fugacity co-efficient of a gas at constant reduced pressure
A. Increases
B. Decreases
C. Remain same
D. Decreases linearly
Answer : A

35. Critical temperature is defined as the temperature above which a gas will
A. Not liquify (barring exceptions)
B. Immediately liquify
C. Never liquify however high the pressure may be
D. None of these
Answer : C

36. For a reversible process involving only pressure-volume work
A. (dF)_T, p < 0
B. (dF)_T, p > 0
C. (dF)_T, p = 0
D. (dA)_T, v < 0
Answer : C

37. The specific heat of saturated water vapour at 100°C is
A. ?
B. -ve
C. 0
D. +ve
Answer : B

38. Pick out the wrong statement:
A. The expansion of a gas in vacuum is an irreversible process
B. An isometric process is a constant pressure process
C. Entropy change for a reversible adiabatic process is zero
D. Free energy change for a spontaneous process is negative
Answer : B

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

40. 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

41. The amount of heat required to decompose a compound into its elements is __________ the heat of formation of that compound from its elements.
A. Less than
B. More than
C. Same as
D. Not related to
Answer : C

42. 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

43. What is the degree of freedom for two miscible (non-reacting) substances in vapor-liquid equilibrium forming an azeotrope?
A. 0
B. 1
C. 2
D. 3
Answer : C

44. For a stable phase at constant pressure and temperature, the fugacity of each component in a binary system __________ as its mole fraction increases.
A. Decreases
B. Increases
C. Remain same
D. Decreases linearly
Answer : B

45. To obtain integrated form of Clausius-Clapeyron equation, ln (P₂/P₁) = (?H_V/R) (1/T₁ - 1/T₂) from the exact Clapeyron equation, it is assumed that the
A. Volume of the liquid phase is negligible compared to that of vapour phase
B. Vapour phase behaves as an ideal gas
C. Heat of vaporisation is independent of temperature
D. All (A), (B) & (C)
Answer : D

46. 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

47. Degrees of freedom at triple point will be
A. 0
B. 1
C. 2
D. 3
Answer : A

48. The Joule-Thomson co-efficient is defined as (?T/?P)_H. Its value at the inversion point is
A. ?
B. 1
C. 0
D. -ve
Answer : C

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

50. 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, ? S₁ and ? S_R are the entropy changes of the system for the irreversible and reversible processes respectively)
A. ? S₁ is always < ? S_R
B. ? S₁ is sometimes > ? S_R
C. ? S₁ is always > ? S_R
D. ? S₁ is always = ? S_R
Answer : C