Thermodynamics Questions and Answers – Temperature-Entropy Plot

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This set of Thermodynamics Multiple Choice Questions & Answers (MCQs) focuses on “Temperature-Entropy Plot”.

1. For a reversible heat transfer and process being adiabatic, which of the following is true?
a) dQ=0
b) dS=0
c) S=constant
d) all of the mentioned
View Answer

Answer: d
Explanation: dQ=0 since process is reversible and adiabatic and dS=dQ/T.
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2. A reversible adiabatic process is an isentropic process.
a) true
b) false
View Answer

Answer: a
Explanation: dQ=0 and dS=0 and hence S=constant.

3. The area under the curve ∫TdS is equal to the
a) work done
b) heat transferred
c) internal energy change
d) none of the mentioned
View Answer

Answer: b
Explanation: Q(reversible)=∫TdS.
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4. Which of the following statement is true?
a) for reversible isothermal heat transfer, Q=t(Sf-Si)
b) for reversible adiabatic process, S=constant
c) both of the mentioned
d) none of the mentioned
View Answer

Answer: c
Explanation: For reversible isothermal heat transfer, T=constant and for reversible adiabatic process, dS=0.

5. A Carnot cycle has following processes.
a) 4 reversible isotherms
b) 4 reversible adiabatics
c) 2 reversible isotherms and 2 reversible adiabatics
d) none of the mentioned
View Answer

Answer: c
Explanation: Two reversible isotherms and two reversible adiabatics constitute a Carnot cycle.
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6. Net work in a Carnot cycle is given by (T1=temperature of heat addition and T2=temperature of heat rejection)
a) (T2-T1)(S1-S4)
b) (T1-T2)(S1-S4)
c) (T1-T2)(S4-S1)
d) none of the mentioned
View Answer

Answer: b
Explanation: Net work=Q1-Q2=(T1-T2)(S1-S4).

7. According to the principle of Caratheodory, the first law in differential form is written as dQ=Adx+Bdy+Cdz.
a) true
b) false
View Answer

Answer: a
Explanation: Here, x,y,z are the three thermodynamic coordinates and A,B,C are the functions of x,y,z.
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8. For adiabatic, reversible transition,
a) Adx+Bdy+Cdz=-1
b) Adx+Bdy+Cdz=1
c) Adx+Bdy+Cdz=0
d) none of the mentioned
View Answer

Answer: c
Explanation: dQ=Adx+Bdy+Cdz=0 for adiabatic and reversible process.

9. For quasi-static, adiabatic path
a) Adx+Bdy+Cdz=TdS
b) Adx+Bdy+Cdz=1
c) Adx+Bdy+Cdz=0
d) none of the mentioned
View Answer

Answer: a
Explanation: This comes from Caratheodory’s theorem.
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10. The infinitesimal change in entropy dS due to reversible heat transfer dQ at temperature T is dS=dQ/T.
a) true
b) false
View Answer

Answer: a
Explanation: For a reversible process, dS=dQ/T .

Sanfoundry Global Education & Learning Series – Thermodynamics.
To practice all areas of Thermodynamics, here is complete set of 1000+ Multiple Choice Questions and Answers.

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Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He is Linux Kernel Developer & SAN Architect and is passionate about competency developments in these areas. He lives in Bangalore and delivers focused training sessions to IT professionals in Linux Kernel, Linux Debugging, Linux Device Drivers, Linux Networking, Linux Storage, Advanced C Programming, SAN Storage Technologies, SCSI Internals & Storage Protocols such as iSCSI & Fiber Channel. Stay connected with him @ LinkedIn | Youtube | Instagram | Facebook | Twitter