Engineering Questions with Answers - Multiple Choice Questions

Environmental Engineering MCQ – Chemical Clarification

1 - Question

Which of the following represents the coagulant pipe in the following figure?
environmental-engineering-questions-answers-chemical-clarification-q1-to-q10
Figure: Flash mixer
a) A
b) B
c) C
d) D

View Answer

Answer: a
Explanation: ‘A’ represents the coagulant pipe which is used for discharging the coagulant into the flash mixer.




2 - Question

Which of the following represents the device which is used for sludge removal in the following figure?
environmental-engineering-questions-answers-chemical-clarification-q1-to-q10
Figure: Flash mixer
a) F
b) E
c) D
d) B

View Answer

Answer: c
Explanation: ‘D’ represents the drain valve which is used for the removal of sludge from the mixer.




3 - Question

 _________ is the average of velocities at a point over a definite period of time.
environmental-engineering-questions-answers-chemical-clarification-q1-to-q10
Figure: Flash mixer
a) Mean velocity
b) Relative velocity
c) Velocity gradient
d) Temporal mean velocity

View Answer

Answer: d
Explanation: Temporal mean velocity is the average of velocities at a point over a definite period of time. It is represented by G.




4 - Question

Which of the following goes to the flocculation tank in the following figure?
environmental-engineering-questions-answers-chemical-clarification-q1-to-q10
Figure: Flash mixer
a) B
b) C
c) E
d) F

View Answer

Answer: b
Explanation: ‘B’ represents the outlet of the mixer which goes to the flocculation tank.




5 - Question

Which of the following is the correct expression regarding temporal mean velocity in the following figure?
environmental-engineering-questions-answers-chemical-clarification-q1-to-q10
Figure: Flash mixer
a) G = (P/μV)1/2
b) G = (P/μV)
c) G = (P/μV)2
d) G = (Pμ/V)1/2

View Answer

Answer: a
Explanation: Temporal mean velocity G = (P/μV)1/2, where P is the power, μ is the dynamic viscosity and V is the volume of the tank. It is measured in per second.




6 - Question

Which of the following is correctly paired in the following figure?
environmental-engineering-questions-answers-chemical-clarification-q1-to-q10
Figure: Flash mixer
a) C – Impeller
b) D – Outlet
c) F – Deflecting wall
d) E – Impeller

View Answer

Answer: d
Explanation: E represents the Impeller which is driven by the electric motor to revolve in the tank.




7 - Question

The speed of impeller in a flash mixer is ___________
environmental-engineering-questions-answers-chemical-clarification-q1-to-q10
Figure: Flash mixer
a) 45rpm
b) 60rpm
c) 110rpm
d) 200rpm

View Answer

Answer: c
Explanation: The speed of impeller in a flash mixer is between 100 to 120 rpm and the propeller type impeller is used.




8 - Question

 ‘C’ in the following figure represents the ________
environmental-engineering-questions-answers-chemical-clarification-q1-to-q10
Figure: Flash mixer
a) Impeller
b) Impeller shaft
c) Deflecting wall
d) Flash mixer wall

View Answer

Answer: c
Explanation: ‘C’ represents the deflecting wall, whereas the boundary below the inlet and outlet of the tank is the flash mixer wall.




9 - Question

The detention period of a flash mixer is _________________
environmental-engineering-questions-answers-chemical-clarification-q1-to-q10
Figure: Flash mixer
a) 2 minutes
b) 30 minutes
c) 1 hour
d) 2 hours

View Answer

Answer: a
Explanation: The detention period of flash mixer lies between 30 seconds to 2 minutes.




10 - Question

Which of the following represents the impeller shaft in the following figure?
environmental-engineering-questions-answers-chemical-clarification-q1-to-q10
Figure: Flash mixer
a) F
b) E
c) C
d) B

View Answer

Answer: a
Explanation: Impeller is connected to impeller shaft which is further connected to electric motor so as to drive the impeller and mixing of coagulant in water takes place.

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