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 19 of 30
- A. x
- B. x + 1
- C. x + 3
- D. x + 2
Explanation: The Gibbs phase rule is F = x - P + 2. Setting the degrees of freedom F to zero gives the maximum equilibrium phases as P = x + 2.
Correct answer: x + 2- A. Pressure of working fluid
- B. Two temperatures only
- C. Mass of the working fluid
- D. Mass and pressure both of the working fluid
Explanation: Carnot efficiency is η = 1 - Tcold/Thot, using absolute temperatures, so it depends only on the two reservoir temperatures.
Correct answer: Two temperatures only- A. 0°C and 760 mm Hg
- B. 15°C and 760 mm Hg
- C. 20°C and 760 mm Hg
- D. 0°C and 1 kgf/cm2
Explanation: In the usual chemical-engineering convention, NTP is 20°C and 1 atm, with 1 atm equal to 760 mm Hg.
Correct answer: 20°C and 760 mm Hg- A. √(2KT/m)
- B. 3KT/m
- C. √(6KT/m)
- D. √(3KT/m)
Explanation: From the kinetic theory of gases, the mean square speed is related by u² = 3KT/m.
Correct answer: √(3KT/m)- A. Friction in the system should be absent
- B. System and surroundings pressure be equal
- C. System and surroundings temperature be equal
- D. None of these
Explanation: A reversible process must have no dissipative effects, particularly friction, and must proceed through infinitesimal driving differences.
Correct answer: Friction in the system should be absent- A. Increases with increase in pressure
- B. None of these
- C. Is independent of temperature
- D. Decreases with increase in temperature
Explanation: For an ideal gas, internal energy depends only on absolute temperature, not independently on pressure.
Correct answer: None of these- A. Critical temperature
- B. Melting point
- C. Both B. and C
- D. Freezing point
Explanation: At the melting point, solid and liquid coexist in equilibrium; the same temperature is called the freezing point when viewed as liquid…
Correct answer: Both B. and C- A. ΔE = ΔH = 0
- B. Only ΔH =0
- C. Only ΔE = 0
- D. dQ = dE
Explanation: For an ideal gas, both internal energy and enthalpy depend only on temperature.
Correct answer: ΔE = ΔH = 0- A. 0
- B. 1
- C. 2
- D. 3
Explanation: A phase is a homogeneous, physically distinct region, and a system may consist entirely of one phase.
Correct answer: 1- A. Is the most efficient of all refrigeration cycles
- B. Has very low efficiency
- C. Both B. and C
- D. Requires relatively large quantities of air to achieve a significant amount of refrigeration
Explanation: Air refrigeration has a low coefficient of performance and requires a high mass flow rate because air has a relatively low refrigeration…
Correct answer: Both B. and C- A. Free energy
- B. Entropy
- C. Refractive index
- D. None of these
Explanation: Free energy and entropy scale with the amount of material and are extensive properties.
Correct answer: Refractive index- A. Infinity
- B. Unity
- C. Negative
- D. Constant
Explanation: At constant temperature, gas-liquid equilibrium follows Henry’s law, so the ratio of dissolved-gas concentration to gas-phase…
Correct answer: Constant- A. 5.2
- B. 6.2
- C. 0.168
- D. Data insufficient, can't be found out
Explanation: For a Carnot refrigerator, COP = T_L/(T_H − T_L), using absolute temperatures. Thus COP = 260.15/(310.15 − 260.15) ≈ 5.2.
Correct answer: 5.2374. Chemical engineering thermodynamics is concerned with the ____________ in/of chemical processes?
- A. Reaction mechanism
- B. Energy transformation from one form to another
- C. Calculation of rates
- D. None of these
Explanation: Thermodynamics tracks heat, work and internal energy, and therefore deals with energy transformations in chemical processes.
Correct answer: Energy transformation from one form to another- A. Fugacity
- B. Activity co-efficient
- C. Free energy
- D. All A, B. & C
Explanation: Fugacity, activity coefficient and free energy are thermodynamic properties or functions whose values generally vary with temperature.
Correct answer: All A, B. & C- A. None of these
- B. Temperature
- C. Pressure
- D. Steam to ethylene ratio
Explanation: The reaction has a change in gaseous moles of Δn = 1 − 2 = −1, so equilibrium conversion depends on pressure as well as temperature and…
Correct answer: None of these- A. Melting of ice
- B. Sudden bursting of a cycle tube
- C. Condensation of alcohol vapor
- D. Evaporation of water
Explanation: A suddenly bursting cycle tube releases gas so rapidly that there is negligible time for heat transfer, making the event approximately…
Correct answer: Sudden bursting of a cycle tube- A. Pressure to pseudocritical pressure
- B. Critical pressure to pressure
- C. Pressure to critical pressure
- D. Pseudocritical pressure to pressure
Explanation: Reduced pressure is defined by comparing the actual pressure with the critical pressure: P_r = P/P_c.
Correct answer: Pressure to critical pressure- A. None of these
- B. Decrease
- C. No change
- D. Increase
Explanation: The liquid phase of wax is more disordered than its solid phase, so melting increases molecular disorder and entropy.
Correct answer: Increase- A. 3
- B. 1
- C. 2
- D. 0
Explanation: For a binary vapour-liquid system, the usual phase rule gives two degrees of freedom, but the azeotropic condition adds one restriction…
Correct answer: 1