Free Chemical Engineering Thermodynamics MCQs with Answers

• A. Molar volume, density, viscosity and boiling point
• B. Refractive index and surface tension
• C. Both A. and B
• D. None of these

Explanation: Molar volume, density, viscosity, boiling point, refractive index, and surface tension do not depend on the amount of substance, so they…

• A. Matter
• B. Energy
• C. Both matter and energy
• D. Neither matter nor energy

Explanation: An isolated system is completely closed to its surroundings, so it exchanges neither mass nor energy.

• A. Solids
• B. Liquids
• C. Gases
• D. All (A), B. & (C)

Explanation: Kopp's rule estimates the heat capacity of a solid compound by adding the atomic heat capacities of its constituent elements.

• A. (T2 - T1)/T2
• B. (T2 - T1)/T1
• C. (T1 - T2)/T2
• D. (T1 - T2)/T1

Explanation: A Carnot engine rejects heat at the lower temperature T1 and receives heat at the higher temperature T2, so η = 1 − T1/T2 = (T2 − T1)/T2.

• A. Phase rule variables are intensive properties
• B. CP and CV are state function
• C. The work done by expansion of a gas in vacuum is zero
• D. Heat and work are both state function

Explanation: Heat and work are path functions, not state functions, because their values depend on how a process occurs.

• A. Turbine
• B. Reversed heat engine
• C. Heat engine
• D. None of these

Explanation: A refrigerator transfers heat from a low-temperature reservoir to a high-temperature reservoir by consuming work.

• A. F = E - TS
• B. F = H - TS
• C. F = H + TS
• D. F = E + TS

Explanation: Gibbs free energy is defined as G = H - TS, where H is enthalpy, T is absolute temperature, and S is entropy.

• A. Internal energy
• B. Enthalpy
• C. Gibbs free energy
• D. Helmholtz free energy

Explanation: For a reversible isothermal steady-flow compression, the heat term is TΔS, so the required work becomes ΔH - TΔS = ΔG.

• A. > 0
• B. 0
• C. < 0
• D. None of these

Explanation: For an irreversible process, entropy is generated, so the entropy change of the combined system and surroundings, or the universe, is…

• A. Prediction of the extent of a chemical reaction
• B. Both B. and C.
• C. Evaluating entropy changes of chemical reaction
• D. Calculating absolute entropies of substances at different temperature

Explanation: The third law assigns zero entropy to a perfect crystal at absolute zero, allowing absolute entropies to be calculated at other…

• A. Molecular size
• B. Volume
• C. Temperature
• D. Pressure

Explanation: For an ideal gas, intermolecular effects are neglected, so internal energy depends only on temperature.

• A. The statement as per Gibbs-Helmholtz
• B. None of these
• C. Henry's law
• D. Called Lewis-Randall rule

Explanation: The Lewis-Randall rule states that a component's fugacity in an ideal mixture equals its mole fraction multiplied by its pure-component…

• A. Volume
• B. Mass
• C. None of these
• D. Critical temperature

Explanation: The principle of corresponding states gives the same compressibility factor and reduced volume for substances at the same reduced…

• A. High temperature and low pressure
• B. Low temperature and low pressure
• C. High temperature and high pressure
• D. Low temperature and high pressure

Explanation: Because the forward reaction is exothermic, lowering the temperature shifts equilibrium toward products.

• A. ds 0
• B. ds = 0
• C. ds = Constant

Explanation: An isolated system has no heat or mass exchange, and at reversible equilibrium its entropy is at a maximum.

• A. Reversible isothermal volume change
• B. Simultaneous heating and expansion of an ideal gas
• C. Cooling of a substance
• D. Heating of a substance

Explanation: This is the ideal-gas entropy relation obtained by combining the temperature and volume contributions, so it applies when temperature and…

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

Explanation: At fixed reduced pressure, increasing reduced temperature generally weakens the relative effect of intermolecular attractions and moves…

• A. Initial concentration of the reactant
• B. Pressure
• C. None of these
• D. Temperature

Explanation: For a given reaction, the equilibrium constant is fixed at a specified temperature and changes when temperature changes.

• A. May exist
• B. Always exists
• C. Never exists
• D. Is difficult to predict

Explanation: For a cycle, the system returns to its initial state, so its change in internal energy is zero and the net heat equals the net work.

• A. Internal energy
• B. All (A), B. & (C)
• C. Entropy
• D. Enthalpy

Explanation: For an incompressible fluid, internal energy is primarily a function of temperature, whereas h = u + Pv includes a pressure-volume term.