Free Chemical Engineering Thermodynamics MCQs with Answers
598 Chemical Engineering Thermodynamics MCQs from Chemical Engineering, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
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598 questions · page 16 of 30
- A. Third law of thermodynamics
- B. Second law of thermodynamics
- C. Nernst heat theorem
- D. Maxwell's relations
Explanation: The third law assigns zero entropy at absolute zero to a perfectly crystalline substance.
Correct answer: Third law of thermodynamics- A. (∂P/∂V)S = (∂P/∂V)T
- B. (∂P/∂V)S = [(∂P/∂V)T]Y
- C. (∂P/∂V)S = y(∂P/∂V)T
- D. (∂P/∂V)S = 1/y(∂P/∂V)T
Explanation: For an ideal gas, the isothermal slope is −P/V, while the reversible adiabatic slope is −γP/V.
Correct answer: (∂P/∂V)S = y(∂P/∂V)T- A. -94 kcal
- B. > -94 kcal
- C. < - 94 kcal
- D. Zero
Explanation: Oxygen is an element in its standard reference state, so its standard enthalpy of formation is defined as zero.
Correct answer: Zero- A. Involves transfer of heat from low temperature to high temperature
- B. Violates second law of thermodynamics
- C. Both A. and B
- D. Neither A. nor B
Explanation: A refrigeration cycle uses work input to transfer heat from a low-temperature region to a high-temperature surroundings.
Correct answer: Involves transfer of heat from low temperature to high temperature- A. 1st
- B. Zeroth
- C. 3rd
- D. None of these
Explanation: The Zeroth Law establishes thermal equilibrium and provides the basis for defining and measuring temperature.
Correct answer: Zeroth- A. Isobaric
- B. Adiabatic
- C. Isothermal
- D. None of these
Explanation: The polytropic work expression contains the factor 1 − n and becomes indeterminate when n = 1, the isothermal case; its work must be…
Correct answer: Isothermal- A. Van Laar equation
- B. Margules equation
- C. Wilson's equation
- D. All A, B. and C
Explanation: Van Laar, Margules, and Wilson equations correlate experimental vapor-liquid equilibrium data to estimate activity coefficients.
Correct answer: All A, B. and C- A. Isothermal
- B. Adiabatic
- C. Isometric
- D. None of these
Explanation: During melting at its melting point, ice and liquid water coexist in equilibrium, so the temperature remains essentially constant while…
Correct answer: Isothermal- A. +ve
- B. 0
- C. -ve
- D. Either of the above three; depends on the nature of refrigerant
Explanation: In a complete refrigeration cycle, the refrigerant returns to its initial state, so internal energy, being a state property, has zero net…
Correct answer: 0- A. A = H - TS
- B. A = H + TS
- C. A = E - TS
- D. None of these
Explanation: Helmholtz free energy is defined using internal energy as A = U − TS. Since U is also denoted by E, this is written here as A = E − TS…
Correct answer: A = E - TS- A. Fugacity
- B. Activity co-efficient
- C. Free energy
- D. None of these
Explanation: Fugacity, activity coefficient, and free energy all generally vary with temperature.
Correct answer: None of these- A. Adiabatic
- B. Isothermal
- C. Isentropic
- D. None of these
Explanation: For expansion between fixed pressure limits, an isothermal path maintains the gas at the highest temperature relative to an adiabatic path…
Correct answer: Isothermal- A. Pressure is constant
- B. Cooling occurs
- C. Heating occurs
- D. Temperature is constant
Explanation: A reversible adiabatic compression has no heat transfer, but the work supplied to the gas raises its internal energy and temperature.
Correct answer: Heating occurs- A. No
- B. Any real
- C. Both B. and C.
- D. Only ideal
Explanation: For an ideal gas, the equation of state gives Cp − Cv = R per mole, independent of the gas temperature or pressure.
Correct answer: Only ideal- A. Temperature
- B. Pressure
- C. Both A. & B.
- D. Neither A. nor B.
Explanation: For an ideal gas, enthalpy and internal energy depend only on temperature, so Cp and Cv are functions of temperature.
Correct answer: Temperature- A. Sublimation
- B. Transition
- C. Fusion
- D. Vaporisation
Explanation: A change from one allotrope or solid form to another is a phase transition, and the associated heat is called the heat of transition.
Correct answer: Transition- A. -ve
- B. ∞
- C. +ve
- D. 0
Explanation: At the inversion temperature, the Joule-Thomson effect changes from heating to cooling, so the coefficient passes through zero.
Correct answer: 0- A. All A , B. & C.
- B. Vapour phase behaves as an ideal gas
- C. Heat of vaporisation is independent of temperature
- D. Volume of the liquid phase is negligible compared to that of vapour phase
Explanation: The integrated Clausius-Clapeyron equation follows by neglecting the liquid volume, treating the vapour as ideal, and taking the heat of…
Correct answer: All A , B. & C.- A. Inversely proportional
- B. Directly proportional
- C. Equal
- D. None of these
Explanation: Activity is defined from fugacity as a = f/f° at a specified temperature and standard-state fugacity f°.
Correct answer: Directly proportional- A. At constant pressure
- B. By expansion in an engine
- C. By throttling
- D. None of these
Explanation: The Linde process uses Joule-Thomson throttling through a valve, with regenerative heat exchange to precool the gas before throttling.
Correct answer: By throttling