Chemical Engineering

Steady-State and Unsteady-State Systems

Question 1
Marks : +2 | -2
Pass Ratio : 100%
Which of the following remains constant in the steady state system?
Mass
Energy
Momentum
Density
Explanation:
In a steady state system what amount of material goes in the same amount comes out, so the overall mass remains constant.
Question 2
Marks : +2 | -2
Pass Ratio : 100%
An unsteady-state system, with 6 liters as initial amount of water in the vessel, water flow in rate is 2 liters/ s and flow out rate is 4 liters/s, what will be the amount of water in the vessel after 1 second?
2 liters
4 liters
6 liters
8 liters
Explanation:
Total amount of water reduced from the vessel in 1 second = (4 – 2)*1 = 2 liters, => Final amount of water = 6 – 2 = 4 liters.
Question 3
Marks : +2 | -2
Pass Ratio : 100%
A fluid enters a vessel at the rate of 10 liters/s, and leaves in two pathways one with 5 liters/s and other with 3 liters/s, then what type of flow it is?
Steady-state
Unsteady-state
Cannot say
None of the mentioned
Explanation:
Since the flow in rate and flow out rate of the fluid are unequal, the system is in unsteady-state.
Question 4
Marks : +2 | -2
Pass Ratio : 100%
The rate flow in and flow out in an unsteady state process are now increased by 10 Kg/s, which will be the change in accumulation?
0
5 Kg/s
10 Kg/s
20 Kg/s
Explanation:
Initial accumulation = rate of flow out – rate of flow in, => Final accumulation = (rate of flow out + 10) – (rate of flow in + 10) = Initial accumulation, => Change in accumulation = 0.
Question 5
Marks : +2 | -2
Pass Ratio : 100%
A reaction occurs in a vessel such that its mass does not change but its temperature is increased, then the system is which of the following?
Steady-state
Unsteady-state
Cannot say
None of the mentioned
Explanation:
For a steady-state system all the properties temperature, pressure, mass should remain constant with respect to time, so it is an unsteady-state process.
Question 6
Marks : +2 | -2
Pass Ratio : 100%
What amount of 57 octane should be mixed with 3 liters of 63 octane to obtain 4 liters of 59 octane?
1 liter
2 liters
2.5 liters
4.5 liters
Explanation:
59*1 = 63*x + 57*(1 – x), => x = 1/3, now 4 = (1/3)*3 + (2/3)*w, => w = 4.5 liters.
Question 7
Marks : +2 | -2
Pass Ratio : 100%
An unsteady-state system, with 10 liters as initial amount of water in the vessel, water flow in rate is 8 liters/ s and flow out rate is 5 liters/s, what will be the amount of water in the vessel after 10 seconds?
10 liters
20 liters
30 liters
40 liters
Explanation:
Amount of water added to the vessel in 10 seconds = (8 – 5)*10 = 30 liters, => Final amount of water = 10 + 30 = 40 liters.
Question 8
Marks : +2 | -2
Pass Ratio : 100%
A fluid enters a vessel at the rate of 10 liters/s, and leaves in two pathways one with 7 liters/s and other with 3 liters/s, then what type of flow it is?
Steady-state
Unsteady-state
Cannot say
None of the mentioned
Explanation:
Since the flow in rate and flow out rate of the fluid are equal, the system is in steady-state.
Question 9
Marks : +2 | -2
Pass Ratio : 100%
In what ratio 57 octane and 63 octane should be mixed to obtain 59 octane?
1:1
2:1
3:1
4:1
Explanation:
59*1 = 63*x + 57*(1 – x), => x= 1/3, => 1 – x = 2/3, => ratio of 57 octane: 63 octane = 2/3:1/3 = 2:1.
Question 10
Marks : +2 | -2
Pass Ratio : 100%
What is the final amount of fluid in the vessel if the system is in steady state?
Same as the initial amount
Twice the initial amount
Zero
None of the mentioned
Explanation:
Since in steady-state the rate of flow in is equal to the rate of flow out, so final amount of fluid in the vessel is same as the initial amount.