Materials Science Questions and Answers – Gibbs Phase Rule

This set of Materials Science Multiple Choice Questions & Answers (MCQs) focuses on “Gibbs Phase Rule”.

1. What is Gibbs phase rule for general system?
a) P = C – 1 – F
b) P = C + 1 – F
c) P + F = C – 2
d) P + F = C + 2
View Answer

Answer: d
Explanation: The number of degrees of freedom, F (no. of independently variable factors), number of components, C, and number of phases in equilibrium, P.

2. What is Gibbs phase rule for metallurgical system?
a) F = C – 1 – P
b) F = C + 1 – P
c) P + F = C – 2
d) P + F = C + 2
View Answer

Answer: b
Explanation: For metallurgical system pressure has no appreciable effect on phase equilibrium and hence, F = C – P + 1.

3. In a single – component condensed system, if degree of freedom is zero, maximum number of phases that can co – exist _________
a) 2
b) 3
c) 0
d) 1
View Answer

Answer: a
Explanation: Given F = 0
Then p = c + 1, c = 1
.: P = 2.
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4. The degree of freedom at a triple point in the unary diagram for water is ________
a) 2
b) 3
c) 0
d) 1
View Answer

Answer: c
Explanation: For three phase system degree of freedom is 0.

5. What is degree of freedom for single – phase fields on the phase diagram?
a) 2
b) 3
c) 0
d) 1
View Answer

Answer: a
Explanation: F = C + 1 – P
F = 3 – P (C = 2)
.:F = 2.
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6. What is degree of freedom when two phases co – exist?
a) 2
b) 3
c) 0
d) 1
View Answer

Answer: d
Explanation: F = C + 1 – P
F = 3 – P (C = 2)
F = 3 – 2 = 1.

7. What is degree of freedom when three phases co – exist?
a) 2
b) 3
c) 0
d) 1
View Answer

Answer: c
Explanation: F = C + 1 – P
F = 3 – P (C = 2)
F = 3 – 3 = 0.
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8. For single component system when degree of freedom is 1(one) then number of phases _______
a) 2
b) 3
c) 0
d) 1
View Answer

Answer: d
Explanation: F = C + 1 – P
F = 2 – P (C = 1)
→ p = 2 – F = 2 – 1 = 1.

9. When α, L and β phase fields touch the isotherm line what are the respective phase compositions?
The respective phase compositions is 8.0 wt%, 71.9 wt%, 91.2 wt% of Ag
a) 8.0 wt%, 71.9 wt%, 91.2 wt% of Ag
b) 8.0 wt%, 91.2 wt%, 71.9 wt% of Ag
c) 71.9 wt%, 91.2 wt%, 8.0 wt% of Ag
d) 91.2 wt%, 8.0 wt%, 71.9 wt% of Ag
View Answer

Answer: a
Explanation: For binary systems, when three phases are present, there will be F = 0, so composition is fixed.
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10. For binary alloy consisting of three phases of non – equilibrium one, What will be the temperature of these phases?
The temperature of phases is same for binary alloy of three phases of non equilibrium one
a) Different
b) Constant
c) Same
d) Two of them will be with one temperature
View Answer

Answer: c
Explanation: One use of the Gibbs phase rule is in analyzing for non – equilibrium conditions by analyzing with above method we come to know (under these Circumstances, three phases will exist only at a single temperature).

Sanfoundry Global Education & Learning Series – Materials Science.

To practice all areas of Materials Science, here is complete set of 1000+ Multiple Choice Questions and Answers.

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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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