Free Chemical Engineering Thermodynamics MCQs with Answers

• A. 0°C
• B. 273°C
• C. 100°C
• D. -273°C

Explanation: The average translational kinetic energy of gas molecules is proportional to absolute temperature, so it approaches zero at 0 K.

• A. Minimum
• B. Maximum
• C. Zero
• D. None of these

Explanation: For an isolated system at equilibrium, entropy is at its maximum, so no spontaneous change can increase it further.

• A. Relative volatility of a mixture of two miscible liquids
• B. Escaping tendencies of the same substance in different phases of a system
• C. Behaviour of ideal gases
• D. None of these

Explanation: Fugacity represents a component's effective escaping tendency from a phase, allowing phase equilibrium to be expressed by equal…

• A. Temperature
• B. Volume
• C. Pressure
• D. Entropy

Explanation: Isobaric means constant pressure, since the prefix iso means equal or constant and bar refers to pressure.

• A. Closed
• B. Non-thermodynamic
• C. Isolated
• D. Open

Explanation: A rotary lime kiln continuously receives limestone and fuel and discharges solids and gases, so mass crosses its boundary.

• A. Increases
• B. Decreases
• C. Remain same
• D. Decreases linearly

Explanation: At fixed temperature and pressure, increasing a component's mole fraction in a stable phase increases its chemical potential and hence its…

• A. Pressure vs. enthalpy
• B. Pressure vs. volume
• C. Enthalpy vs. entropy
• D. Temperature vs. entropy

Explanation: A Mollier chart is the enthalpy-entropy diagram, commonly written as an h-s chart.

• A. ∞
• B. 0
• C. -ve
• D. +ve

Explanation: For an ideal gas, isothermal expansion increases volume, and the entropy change is ΔS = nR ln(V₂/V₁), which is positive when V₂ exceeds…

• A. Geometric
• B. Arithmetic
• C. Logarithmic
• D. Harmonic

Explanation: With intercooling back to the initial temperature, minimum total compression work occurs when the pressure ratios in both stages are…

• A. Zero
• B. Unity
• C. Infinity
• D. An indeterminate value

Explanation: As pressure approaches zero, a real gas approaches ideal-gas behaviour, and its fugacity approaches its pressure.

• A. Process must be isobaric
• B. Temperature must decrease
• C. Both B. and C.
• D. Process must be adiabatic

Explanation: Using ΔU = Q − W, a decrease in internal energy equal to the work done by the system gives Q = 0, so the process is adiabatic.

• A. Energy
• B. Momentum
• C. Heat
• D. Work

Explanation: The first law applies conservation of energy, accounting for energy entering or leaving a system as heat and work.

• A. Is zero
• B. Decreases whereas the entropy increases
• C. Increases
• D. And entropy both decrease

Explanation: At constant temperature and pressure, spontaneity requires Gibbs free energy to decrease, while the entropy of the universe increases.

• A. Chemical potential
• B. Fugacity
• C. Both A. and B
• D. Neither A. nor B

Explanation: Phase equilibrium requires the chemical potential of each component to be equal in every phase.

• A. Temperature
• B. Pressure
• C. Composition
• D. All (A), B. and (C)

Explanation: For an ideal solution, the chemical potential contains the term RT ln xᵢ, while the standard-state chemical potential depends on…

• A. Isometric
• B. Polytropic
• C. Isentropic
• D. Isobaric

Explanation: A reversible process obeying PVⁿ = constant is called polytropic. The special values n = 1 and n = γ correspond to isothermal and…

• A. Has same volume
• B. Expands
• C. Contracts
• D. May contract or expand

Explanation: Water has its minimum specific volume, or maximum density, at about 4°C.

• A. Less
• B. More or less depending upon the extent of work done
• C. Same
• D. More

Explanation: For compression between the same initial and final volumes, an adiabatic path has a higher pressure than an isothermal path because the…

• A. Isothermal
• B. Adiabatic
• C. Neither A. nor B
• D. Both A. & B

Explanation: PV = RT is the ideal-gas equation of state, so it applies at every equilibrium state of an ideal gas, whether the process is isothermal or…

• A. Virial co-efficients are function of temperature only
• B. Virial co-efficients 'B' represents three body interactions
• C. Virial co-efficients are universal constants
• D. For some gases, Virial equations and ideal gas equations are the same

Explanation: For a specified gas, virial coefficients are primarily functions of temperature, while their values also depend on the gas.