Thermodynamics Questions and Answers – Maxwell’s Equations and TDS Equations

This set of Thermodynamics Problems focuses on “Maxwell’s Equations and TDS Equations”.

1. If a relation exists among variables x,y,z then z may be expressed as a function of x and y as, dz=Mdx+Ndy .
a) true
b) false
View Answer

Answer: a
Explanation: Here, M,N and z are functions of x and y.

2. A pure substance which exists in a single phase has ____ independent variables.
a) zero
b) one
c) two
d) three
View Answer

Answer: c
Explanation: Of all the quantities, any one can be expressed as a function of any two others.

3. Which of the following relation is correct?
a) dU=TdS-pdV
b) dH=TdS+Vdp
c) dG=Vdp-SdT
d) all of the mentioned
View Answer

Answer: d
Explanation: These relations are true for a pure substance which undergoes an infinitesimal reversible process.
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4. Maxwell’s equations consists of ____ equations.
a) four
b) three
c) two
d) one
View Answer

Answer: a
Explanation: Maxwell’s equations consists of four equations.

5. Which of the following is not a Maxwell equation?
a) (∂T/∂V) = -(∂p/∂S)
b) (∂T/∂p) = -(∂V/∂S)
c) (∂p/∂T) = (∂S/∂V)
d) (∂V/∂T) = -(∂S/∂p)
View Answer

Answer: b
Explanation: The correct equation is (∂T/∂p) = (∂V/∂S).
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6. The condition for exact differential is
a) (∂N/∂y) = (∂M/∂x)
b) (∂M/∂y) = (∂N/∂x)
c) (∂M/∂y) = -(∂N/∂x)
d) all of the mentioned
View Answer

Answer: b
Explanation: This is the condition for perfect or exact differential and here M and N are the functions of x and y.

7. The first TdS equation is
a) TdS=Cv*dT + T(∂T/∂p)dV
b) TdS=Cv*dT – T(∂p/∂T)dV
c) TdS=Cv*dT + T(∂p/∂T)dV
d) TdS=Cv*dT – T(∂T/∂p)dV
View Answer

Answer: c
Explanation: This equation comes when entropy is defined as a function of T and V and using Cv and Maxwell’s third equation.
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8. The second TdS equation is
a) TdS=Cp*dT + T(∂V/∂T)dp
b) TdS=Cp*dT – T(∂V/∂T)dp
c) TdS=Cp*dT + T(∂T/∂V)dp
d) TdS=Cp*dT – T(∂T/∂V)dp
View Answer

Answer: b
Explanation: This equation comes when entropy is defined as a function of T and p and using Cp and Maxwell’s fourth equation.

9. Which of the following is true?
a) (∂p/∂V)*(∂V/∂T)*(∂T/∂p)= infinity
b) (∂p/∂V)*(∂V/∂T)*(∂T/∂p)= 0
c) (∂p/∂V)*(∂V/∂T)*(∂T/∂p)= 1
d) (∂p/∂V)*(∂V/∂T)*(∂T/∂p)= -1
View Answer

Answer: d
Explanation: This is the relation between the thermodynamic variables, p,V and T.
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10. For getting TdS equations, we assume entropy to be a function of T and V and also of T and p.
a) true
b) false
View Answer

Answer: a
Explanation: For first TdS equation, we assume entropy as a function of T and V and for second TdS equation, we assume entropy as a function of T and p .

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

If you find a mistake in question / option / answer, kindly take a screenshot and email to [email protected]

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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 lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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