Chemical Engineering Puzzles on “Solving Material and Energy Balances Using Process Simulators”.
1. What are the number of degrees of freedom if the number of variables and number of equations are 10 and 8 respectively?
a) 2
b) 8
c) 10
d) 18
Answer: a
Clarification: Number of degrees of freedom = 10 – 8 = 2.
2. What are the number of degrees of freedom if the number of variables and number of equations are 15 and 10 respectively?
a) 5
b) 10
c) 15
d) 25
Answer: a
Clarification: Number of degrees of freedom = 15 – 10 = 5.
3. What are the number of degrees of freedom if the number of variables and number of equations are 15 and 5 respectively?
a) 5
b) 10
c) 15
d) 20
Answer: b
Clarification: Number of degrees of freedom = 15 – 5 = 10.
4. What are the number of degrees of freedom if the number of variables and number of equations are 18 and 7 respectively?
a) 7
b) 9
c) 11
d) 15
Answer: c
Clarification: Number of degrees of freedom = 18 – 7 = 11.
5. What are the number of degrees of freedom if the number of variables and number of equations are 21 and 9 respectively?
a) 7
b) 9
c) 10
d) 12
Answer: d
Clarification: Number of degrees of freedom = 21 – 9 = 12.
6. Degrees of freedom calculation treat which kind of variables?
a) Intensive
b) Extensive
c) Both
d) None of the mentioned
Answer: a
Clarification: Degrees of freedom calculation treat intensive variables.
7. Which of the following cannot be treated as a variable for degrees of freedom calculation?
a) Temperature
b) Pressure
c) Volume
d) Work
Answer: c
Clarification: Since Volume is an extensive variable, it cannot be treated as a variable for degrees of freedom calculation.
8. Which of the following cannot be treated as a variable for degrees of freedom calculation?
a) Specific enthalpies
b) Heat
c) Extent of reaction
d) Entropy
Answer: d
Clarification: Since entropy is an extensive variable, it cannot be treated as a variable for degrees of freedom calculation.
9. What are the number of variables associated with a process stream, if the number of species in the stream are 2?
a) 1
b) 2
c) 3
d) 4
Answer: d
Clarification: Nv = Nsp + 2 = 2 + 2 = 4.
10. What are the number of compositions associated with a process stream, if the number of species in the stream are 2?
a) 1
b) 2
c) 3
d) 4
Answer: a
Clarification: Number of compositions = Nsp – 1 = 2 – 1 = 1.
11. What is the number of compositions associated with a process stream, if the number of species in the stream is 4?
a) 1
b) 2
c) 3
d) 4
Answer: c
Clarification: Number of compositions = Nsp – 1 = 4 – 1 = 3.
12. What are the number of variables associated with a process stream, if the number of species in the stream are 5?
a) 1
b) 3
c) 5
d) 7
Answer: d
Clarification: Nv = Nsp + 2 = 5 + 2 = 7.
13. What are the number of equations associated with 3 process stream, if the number of species in the stream are 2?
a) 3
b) 4
c) 6
d) 12
Answer: d
Clarification: Number of equations = 3(2 + 2) = 12.
14. What are the number of equations associated with 2 process stream, if the number of species in the stream are 3?
a) 2
b) 3
c) 5
d) 10
Answer: d
Clarification: Number of equations = 2(3 + 2) = 10.
15. What are the number of equations associated with 4 process stream, if the number of species in the stream are 2?
a) 4
b) 8
c) 16
d) 24
Answer: c
Clarification: Number of equations = 4(2 + 2) = 12.