Basic Chemical Engineering Multiple Choice Questions & Answers (MCQs) on “Open and Closed Systems”.
1. Which of the following is constant in a closed system?
a) Energy
b) Mass
c) Temperature
d) Momentum
Answer: b
Clarification: A material neither leaves nor enters a closed system.
2. How is the boundary wall of a closed system?
a) Impermeable
b) Permeable
c) Rigid
d) None of the mentioned
Answer: a
Clarification: Since the matter is not allowed to cross the boundary wall of a closed system, so the wall is impermeable.
3. Desert Cooler is an example of which of the following?
a) Closed System
b) Open System
c) Isolated System
d) None of the mentioned
Answer: b
Clarification: Since water is filled and then it vaporizes in desert cooler, this means the material is flowing in and out of the system, so it is an open system.
4. A jar filled with water is an example of which of the following?
a) Closed System
b) Open System
c) Isolated System
d) None of the mentioned
Answer: a
Clarification: Since water is neither leaving nor entering the jar, this means it is a closed system.
5. A pressure cooker is an example of which of the following?
a) Closed System
b) Open System
c) Isolated System
d) None of the mentioned
Answer: b
Clarification: Since steam is expelled outside in the cooker as the temperature increase, it is an open system.
6. A country is an example of which of the following?
a) Closed System
b) Open System
c) Isolated System
d) None of the mentioned
Answer: b
Clarification: Since a man can leave or enter a country it is an example of an open system.
7. An egg is an example of which of the following?
a) Closed System
b) Open System
c) Isolated System
d) None of the mentioned
Answer: a
Clarification: Since matter is neither entering nor leaving an egg, it’s a closed system.
8. The human body is an example of which of the following?
a) Closed System
b) Open System
c) Isolated System
d) None of the mentioned
Answer: b
Clarification: Since air, water and food are going in and out of a human body, it’s an open system.
9. What is the accumulation in the system after 10 second if the out flow and in flow rates are 10 g/s and 15 g/s?
a) 5 g
b) 10 g
c) 50 g
d) 100 g
Answer: c
Clarification: Accumulation = 10*(15 – 10) = 50 g.
10. What is the accumulation in the system after 4 second if the out flow and in flow rates are 3 g/s and 8 g/s?
a) 12 g
b) 20 g
c) 32 g
d) 40 g
Answer: b
Clarification: Accumulation = 4*(8 – 3) = 20 g.
11. The flow in rate of A is 5 mole/s, it undergoes a reaction A -> 2B, what are the moles of B that comes out after 5 seconds?
a) 5
b) 10
c) 25
d) 50
Answer: d
Clarification: Moles of B = 5*5*2 = 50.
12. The flow in rate of A is 8 mole/s, it undergoes a reaction 3A -> B, what are the moles of B that comes out after 6 seconds?
a) 5
b) 8
c) 10
d) 16
Answer: d
Clarification: Moles of B = 8*6/3 = 16.
13. The flow in rate of A and B are 5 mole/s and 10 mole/s respectively, which under goes reaction A + 2B -> 3C, what is the flow out rate of C?
a) 5 mole/s
b) 10 mole/s
c) 15 mole/s
d) 20 mole/s
Answer: c
Clarification: Rate of C = 3*5 = 15 mole/s.
14. The flow in rate of A and B are 4 mole/s and 8 mole/s respectively, which under goes reaction A + B -> 3C, what is the flow out rate of C?
a) 4 mole/s
b) 8 mole/s
c) 12 mole/s
d) 24 mole/s
Answer: c
Clarification: Rate of C = 4*3 = 12 mole/s.
15. The flow in rate of A and B are 8 mole/s and 10 mole/s respectively, which under goes reaction 4A + 5B -> 3C, what is the flow out rate of C?
a) 4 mole/s
b) 6 mole/s
c) 8 mole/s
d) 10 mole/s
Answer: b
Clarification: Flow out rate of C = 3*2 = 6 mole/s.