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Chemical Engineering Thermodynamics MCQ Questions & Answers | Chemical Engineering

Learn Chemical Engineering Thermodynamics MCQ questions & answers are available for a Chemical Engineering students to clear GATE exams, various technical interview, competitive examination, and another entrance exam. Chemical Engineering Thermodynamics MCQ question is the important chapter for a Chemical Engineering and GATE students. Page-4 section-1

Each section contains 100 MCQs on Chemical Engineering Thermodynamics .
31
The Maxwell relation derived from the differential expression for the Helmholtz free energy (dA) is
Discuss
Answer & Solution
Answer: Option D
Solution:
Helmholtz function :
\[\begin{array}{l} A = U - TS\\ \Rightarrow dA = - PdV - SdT \end{array}\]
So, we can derive the Maxwell function : \[{\left( {\frac{{\partial P}}{{\partial T}}} \right)_V} = {\left( {\frac{{\partial S}}{{\partial V}}} \right)_T}\]
32
Which of the following processes can not be made reversible even under ideal condition of operation?
Discuss
Answer & Solution
Answer: Option A
Solution:
A reversible process means the process in which both system and surroundings both should be restored to their original conditions when the system is bought to initial conditions. Since in case of free expansion of gas it is not possible to bring back the surroundings to initial state when system is brought back to initial conditions we call it as an irreversible process.
33
Heat is added at constant pressure in an ideal __________ cycle.
Discuss
Answer & Solution
Answer: Option D
Solution:
In both Rankine and Brayton cycle the heat is added at constant pressure.
34
Heat is added at constant temperature in an ideal __________ cycle.
Discuss
Answer & Solution
Answer: Option A
Solution:
Heat is added at constant temperature in an ideal Stirling cycle.
35
The standard state of a gas (at a given temperature) is the state in which fugacity is equal to
Discuss
Answer & Solution
Answer: Option C
Solution:
The standard state of an gas is taken as ideal gas state where the fugacity is equal to pressure and the pressure is usually taken as $$1,$$ similarly the activity under ideal state is equal to $$1$$ since the activity is the ratio of fugacity at conditions of our interest to the fugacity at standard state and we are taking the standard state as pressure $$= 1$$
So, activity = fugacity = 1.
36
For a constant volume process __________ by the system is used only to increase the internal energy.
Discuss
Answer & Solution
Answer: Option A
No explanation is given for this question. Let's Discuss on Board
37
Which of the following is not a common refrigerant?
Discuss
Answer & Solution
Answer: Option B
Solution:
As ethylene has flammable characters it is not commonly used as a refrigerant.
38
Which of the following is not a reversible process ?
Discuss
Answer & Solution
Answer: Option C
Solution:
Since the entropy of mixing is positive we can say the mixing process or solution formation process is an irreversible process.
39
For spontaneous changes in an isolated system (S = entropy)
Discuss
Answer & Solution
Answer: Option C
Solution:
By second law of thermodynamics the \[TdS \ge \delta Q\]
For an isolated system \[\delta Q = 0\]
\[ \Rightarrow \] for an irreversible (nothing but spontaneous process) \[dS > 0\]   and for an reversible (or the system at equilibrium) \[dS = 0\]
40
A gas performs the maximum work, when it expands
Discuss
Answer & Solution
Answer: Option C
Solution:
The Isobaric, isothermal and adiabatic process represented in $$P – V$$ as the following.
Since, area under $$P-V$$   plot for isobaric process is more than the isothermal and adiabatic process the work done in isobaric process is highest.