Multiple Choice Questions and Answers on Chemical Engineering Thermodynamics
01. Pick out the wrong statement.
(A) A closed system does not permit exchange of mass with its surroundings but may permit exchange of energy.
(B) An open system permits exchange of both mass and energy with its surroundings
(C) The term microstate is used to characterise an individual, whereas macro-state is used to designate a group of micro-states with common characteristics
(D) None of the above
Answer: Option D
02. 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: Option A
03. Pick out the wrong statement.
(A) An ideal liquid or solid solution is defined as one in which each component obeys Raoult’s law
(B) If Raoult’s law is applied to one component of a binary mixture; Henry’s law or Raoult’s law is applied to the other component also
(C) Henry’s law is rigorously correct in the limit of infinite dilution
(D) None of these
Answer: Option D
04. Which of the following is an undesirable characteristic of a refrigerant?
(A) It should be non-explosive
(B) It should have a sub-atmospheric vapor pressure at the temperature in refrigerator coils
(C) Its vapor pressure at the condenser temperature should be very high
(D) None of these
Answer: Option B
05. Work done may be calculated by the expression ∫ p dA for __________ processes.
(A) Non-flow reversible
(B) Adiabatic
(C) Both (A) and (B)
(D) Neither (A) nor (B)
Answer: Option C
06. Sound waves propagation in air exemplifies an __________ process.
(A) Adiabatic
(B) Isothermal
(C) Isometric
(D) None of these
Answer: Option A
07. Pick out the correct statement.
(A) Like internal energy and enthalpy, the absolute value of standard entropy for elementary substances is zero
(B) Melting of ice involves increase in enthalpy and a decrease in randomness
(C) The internal energy of an ideal gas depends only on its pressure
(D) Maximum work is done under reversible conditions
Answer: Option D
08. 1m3 of an ideal gas at 500 K and 1000 kPa expands reversibly to 5 times its initial volume in an insulated container. If the specific heat capacity (at constant pressure) of the gas is 21 J/mole . K, the final temperature will be
(A) 35 K
(B) 174 K
(C) 274 K
(D) 154 K
Answer: Option C
09. Pick out the correct statement.
(A) Entropy and enthalpy are path functions
(B) In a closed system, the energy can be exchanged with the surrounding, while matter cannot be exchanged
(C) All the natural processes are reversible in nature
(D) Work is a state function
Answer: Option C
10. 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: Option C
11. __________ does not change during phase transformation processes like sublimation, melting & vaporisation.
(A) Entropy
(B) Gibbs free energy
(C) Internal energy
(D) All (A), (B) & (C)
Answer: Option B
12. 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: Option C
13. 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: Option B
14. Lenz’s law results from the law of conservation of
(A) Mass
(B) Momentum
(C) Energy
(D) None of these
Answer: Option C
15. 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: Option C
16. 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: Option D
17. One ton of refrigeration capacity is equivalent to the heat removal rate of
(A) 50 kcal/hr
(B) 200 BTU/hr
(C) 200 BTU/minute
(D) 200 BTU/day
Answer: Option C
18. 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: Option B
19. Entropy, which is a measure of the disorder of a system, is:
(A) Independent of pressure
(B) Independent of temperature
(C) Zero at absolute zero temperature for a perfect crystalline substance
(D) All (A), (B) & (C)
Answer: Option C
20. A refrigerator works on the principle of __________ law of thermodynamics.
(A) Zeroth
(B) First
(C) Second
(D) Third
Answer: Option C
21. Cv is given by
(A) (∂E/∂T)V
(B) (∂E/∂V)T
(C) (∂E/∂P)V
(D) (∂V/∂T)P
Answer: Option A
22. Gibbs free energy (G) is represented by, G = H – TS, whereas Helmholtz free energy, (A) is given by, A = E – TS. Which of the following is the Gibbs-Helmholtz equation?
(A) [∂(G/T)/∂T] = – (H/T2)
(B) [∂(A/T)/∂T]V = – E/T2
(C) Both (A) and (B)
(D) Neither (A) nor (B)
Answer: Option C
23. There is a change in __________ during the phase transition.
(A) Volume
(B) Pressure
(C) Temperature
(D) All a, b & c
Answer: Option
A 24. In Joule-Thomson porous plug experiment, the
(A) Enthalpy does not remain constant
(B) Entire apparatus is exposed to surroundings
(C) Temperature remains constant
(D) None of these
Answer: Option D
25. Forward reaction will be favoured for the exothermic reaction, represented by CO + H2O ⇌ CO2 + H2, by
(A) Low temperature and high pressure
(B) Low temperature and low pressure
(C) High temperature and high pressure
(D) High temperature and low pressure
Answer: Option A