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Multiple choice question for engineering

Set 1

1. Which gas is mainly produced due to incomplete burning of wood?
a) CO
b) SO2
c) NO2
d) NO3

View Answer

Answer: a [Reason:] CO is the colorless, odorless, toxic gas produced due to incomplete burning of wood.

2. Which of the following is involved in production of carboxy haemoglobin?
a) CO
b) SO2
c) NO2
d) NO3

View Answer

Answer: a [Reason:] CO + Blood ——> Carboxy haemoglobin (Pink color).

3. Which of the following is a liquid form of aerosol?
a) Fume
b) Dust
c) Mist
d) Smoke

View Answer

Answer: c [Reason:] Mist is a liquid form of aerosol whereas, Fume, Dust and Smoke are a solid form of aerosol.

4. X ray films are a source of which of the following gas?
a) SO2
b) CO2
c) NO2
d) SO3

View Answer

Answer: c [Reason:] NO2 is produced from X ray film. It causes irritation to eyes and cause respiratory disease.

5. The maximum size of fly ash is
a) 1μm
b) 100μm
c) 1000μm
d) 10μm

View Answer

Answer: c [Reason:] Fly ash is a finely divided particle produced from the combustion of coal. Its maximum size is 1000μm.

6. Which of the following leads to a disease called broncho spasm?
a) SO2
b) SO3
c) SO4
d) CO2

View Answer

Answer: b [Reason:] SO3 reacts with body fluids forming H2SO4 leading to Broncho spasm.

7. The minimum size of smoke particle is
a) 0.2μm
b) 1μm
c) 0.8μm
d) 0.5μm

View Answer

Answer: d [Reason:] Smoke is produced due to incomplete combustion of coal. Its size lies between 0.5μm to 1μm.

8. Which of the following is a secondary air pollutant?
a) SPM
b) PAN
c) SO2
d) NO2

View Answer

Answer: b [Reason:] Peroxy Acetyl Nitrate is a secondary air pollutant whereas, Suspended Particulate Matter, SO2 and NO2 are primary air pollutants.

9. The permissible concentration of PM 10 in the air is
a) 60μg/m3
b) 40μg/m3
c) 50μg/m3
d) 20μg/m3

View Answer

Answer: a [Reason:] The permissible concentration of PM 10 in air is 60μg/m3 whereas of PM 2.5 is 40μg/m3.

Set 2

1. The plot of total dynamic head and discharge of a pump is called
a) Dynamic head curve
b) System head curve
c) Pump curve
d) Discharge curve

View Answer

Answer: b [Reason:] The plot of total dynamic head and discharge of a pump is called system head curve and each point on it denotes the head which consists of total static head, head loss in suction and delivery pipe.

2. _______ is the point of intersection of system head curve with the characteristic curve of the pump.
a) Discharge point
b) Operating point
c) Velocity head
d) Pumping point

View Answer

Answer: b [Reason:] The operating point is the point of intersection of system head curve with the head – discharge characteristic curve of the pump. It is also called as operating range.

3. Which of the following is not included in the friction head?
a) Head Loss in entire length of piping
b) Total static head
c) Head Loss in bend tees
d) Head Loss in valves

View Answer

Answer: b [Reason:] The friction head is the sum of head Loss in the entire length of piping, head Loss in bend tees and head Loss in valves.

4. When the pumps are in parallel operation
a) H = H1 + H2
b) 1/H = 1/H1 +1/ H2
c) Q = Q1 + Q2
d) 1/Q = 1/Q1 + 1/Q2

View Answer

Answer: c [Reason:] When the pumps are in parallel operation, then the total discharge is equal to the sum of the discharges by each pump i.e Q = Q1 + Q2.

5. When the pumps are in series operation
a) H = H1 + H2
b) 1/H = 1/H1 +1/ H2
c) Q = Q1 + Q2
d) 1/Q = 1/Q1 + 1/Q2

View Answer

Answer: a [Reason:] When the pumps are in series operation, then at a given discharge, total head is equal to the sum of heads added by each pump i.e H = H1 + H2.

6. The efficiency of pump at half load is
a) 50%
b) 70%
c) 80%
d) 100%

View Answer

Answer: b [Reason:] The efficiency of a pump depends on the amount of load. At half load, the efficiency of the pump is 70%.

7. The efficiency of the pump at quarter load is
a) 50%
b) 70%
c) 80%
d) 100%

View Answer

Answer: a [Reason:] The efficiency of the pump at quarter load is 50% and at full load, the efficiency of the pump is 80%.

8. The installed capacity of the pump does not depend on which of the following?
a) The maximum rate of hourly demand
b) Balancing storage
c) Power of pump
d) Operation schedule

View Answer

Answer: c [Reason:] The installed capacity of the pump depends on three factors, namely- balancing storage, the maximum rate of hourly demand and the operation schedule. The installed capacity of the pump is kept larger than the maximum rate of demand.

9. State whether the following statement is true or false.
If the diameter of pumping mains decreases ,then the total dynamic head will increase.
a) True
b) False

View Answer

Answer: a [Reason:] If the diameter of pumping mains decreases, then the velocity of flow will increase for a given fixed discharge resulting in increase of friction head loss and velocity head and ultimately increases the total dynamic head.

Set 3

1. The impeller in the volute pump is surrounded by
a) Discharge pipe
b) Throat
c) Suction pipe
d) Volute chamber

View Answer

Answer: d [Reason:] The impeller in the volute pump is surrounded by a spiral shaped casing called as volute chamber. The shape of the casing is such that the sectional area of flow around impeller increases from the tongue to delivery tube.

2. The advance version of volute chamber is designed by
a) V. Richardson
b) J. Thomson
c) Darcy Weisbach
d) Bernoulli

View Answer

Answer: b [Reason:] The advance version of volute chamber is designed by J. Thomson where a circular chamber called vortex chamber is provided between the impeller and the volute chamber.

3. Consider the following statements regarding vortex chamber.
1. Reduce the velocity of the pump
2.Convert pressure energy into kinetic energy
3. Decrease the efficiency of the pump
Which of the above statement is correct?
a) Only 1
b) Only 2
c) Only 3
d) 1, 2, 3

View Answer

Answer: a [Reason:] The vortex chamber reduces the velocity of pump, converts the kinetic energy into pressure energy and increase the efficiency of the pump.

4. A diffuser pump is also called as _______ pump.
a) Reciprocating pump
b) Volute pump
c) Turbine pump
d) Rotary pump

View Answer

Answer: c [Reason:] A diffuser pump is a reverse pump, so it is also called as turbine pump. It contains a series of guide vanes surrounding the impeller.

5. Depending on the number of impellers, the centrifugal pump is divided into ____ types.
a) Two
b) Three
c) Four
d) Six

View Answer

Answer: a [Reason:] The centrifugal pump is divided into a single stage and multistage pump depending on the number of impellers.

6. The each stage in centrifugal pump increase the head by ___
a) 10m
b) 20m
c) 30m
d) 60m

View Answer

Answer: c [Reason:] The each stage in centrifugal pump increase the head from 30 to 45m. There can be six stages in a centrifugal pump.

7. Radial flow pump is a pump classified on the basis of
a) Direction of flow
b) Number of impellers
c) Number of entrances to the impeller
d) On the basis of shaft

View Answer

Answer: a [Reason:] Depending on the basis of the direction of flow, the centrifugal pump is divided into the radial flow pump, mixed flow pump and axial flow pump.

8. Which of the following type of pump is based on the number of entrances to the impeller?
a) Single stage pump
b) Single suction pump
c) Mixed flow pump
d) Horizontal pump

View Answer

Answer: b [Reason:] Based on the number of entrances to the impeller, the centrifugal pump is divided into single suction and double suction pump. In a single suction pump, the liquid enters from one side of the impeller.

9. The specific speed of a pump is given by
a) NQ1/2 / H 2
b) NQ1/2 / H 3/4
c) NQ/ H3/4
d) NQ 1/2 / H1/4

View Answer

Answer: b [Reason:] The specific speed of a centrifugal pump is given by NQ1/2 / H3/4 Where, N is the rotational speed in rates per minute, Q is the discharge in litres/Sec and H is the head in metres.

10. When the specific speed of the pump is <2600, the type of pump is
a) Reciprocating pump
b) Centrifugal pump
c) Mixed flow pump
d) Axial flow pump

View Answer

Answer: b [Reason:] The specific speed of the pump is given by NS = NQ 1/2 / H3/4 and when NS > 2600, the type of pump is centrifugal pump.

Set 4

1. Which of the following is termed as free available chlorine?
a) Hypochlorous acid
b) Hypochlorite ions
c) Molecular chlorine
d) Hypochlorous acid, Hypochlorite ions, Molecular chlorine

View Answer

Answer: d [Reason:] The chlorine existing in water as hypochlorous acid, hypochlorite ions, molecular chlorine is termed as free available chlorine.

2. At what pH, chlorine exists as molecular chlorine?
a) 3
b) 5
c) <5
d) <10

View Answer

Answer: c [Reason:] When chlorine is added to water, the chlorine acts as molecular chlorine only when its pH is less than 5.

3. When the pH is between 5 and 10, the chlorine in the water acts as ______
a) Hypochlorous acid
b) Hypochlorite ions
c) Molecular chlorine
d) Hypochlorous acid hypochlorite ions

View Answer

Answer: d [Reason:] When the pH is between 5 and 10, the chlorine in the water acts as hypochlorous acid and hypochlorite ions. As pH increases, the concentration of hypochlorous acid decreases while of hypochlorite ions increases.

4. At what pH, chlorine in water acts as only hypochlorite ions?
a) <5
b) >5
c) >10
d) <3

View Answer

Answer: c [Reason:] HOCl <------> H+ + HOCl Where, HOCl is hypochlorous acid and HOCl is hypochlorite ions. At pH<10, only HOCl is produced.

5. The hypochlorous acid is ______ times effective as hypochorite ions.
a) 10
b) 30
c) 50
d) 80

View Answer

Answer:d [Reason:] The hypochlorous acid is 80 times more effective as hypochorite ions, so the pH of water to be treated should be less than 7 to prevent the ionization of it.

6. Chlorine which gets consumed in the oxidation of impurities before disinfection is
a) Free chlorine
b) Residual chlorine
c) Chlorine demand
d) Residual demand

View Answer

Answer: c [Reason:] Chlorine has the oxidizing power which oxidizes organic and inorganic impurities present in water and the amount of chlorine, which gets consumed before disinfection is called as chlorine demand.

7. The chlorine, which serve as a disinfectant is
a) Free chlorine
b) Free Residual chlorine
c) Chlorine demand
d) Residual demand

View Answer

Answer: b [Reason:] When chlorine demand is fulfilled, then chlorine is available s free residual chlorine, which contains hypochlorous acid and hypochlorite ions.

8. The permissible limit of free residual chlorine is
a) 0.02ppm
b) 0.2ppm
c) 1ppm
d) 2ppm

View Answer

Answer: b [Reason:] The water is satisfactorily disinfected if the free residual chlorine is 0.2 ppm at the contact period of 10 minutes.

9. What is the chemical formula of bleaching powder?
a) Ca (OCl)2
b) Ca (OCl)
c) Ca (OCl)3
d) CaCl2

View Answer

Answer: a [Reason:] The chemical formula of bleaching powder is Ca (OCl)2. It is called as chlorinated lime.

10. Bleaching powder contains ______ of available chlorine.
a) 16%
b) 33.3%
c) 66.6%
d) 99.9%

View Answer

Answer: b [Reason:] Bleaching powder contains 33.3% of available chlorine. It loses its strength during storage and therefore, it is used during emergency conditions.

11. The process of chlorination with hypochlorites is called
a) Super chlorination
b) Pre chlorination
c) Post chlorination
d) Hypo-chlorination

View Answer

Answer: d [Reason:] The process of chlorination with hypochlorites is called Hypo-chlorination. Hypochlorites are applied to water as a solution by the hypochlorite feeding apparatus.

12. Normally, the ratio of ammonia and chlorine in chloramine is
a) 1:1
b) 1:2
c) 1:4.5
d) 1:3.5

View Answer

Answer: c [Reason:] Normally, the ratio of ammonia and chlorine in chloramine is 1:4.5. They are more effective than chlorine.

13. Which type of chloramine is formed when pH of water is 4.4?
a) Monachloramine
b) Dichloramine
c) Trichloramine
d) Both monochloramine and dichloramine

View Answer

Answer: b [Reason:] When the pH<4.4, then trichloramine is formed and when pH lies in the range 4.4-5, then only dichloramine is formed.

14. What is the contact period for disinfection with chloramine?
a) 1hour
b) 2hours
c) 3hours
d) 4hours

View Answer

Answer: b [Reason:] The disinfecting reaction with chloramine are slower than with chlorine alone, so the contact period of 2 hours is provided.

Set 5

environmental-engineering-questions-answers-construction-imhoff-tank-q1-to-q9
Figure: Imhoff tank

Answer the following question using the above figure.

1. Which of the following is represented by C?
a) Outlet
b) Digestion chamber
c) Gas chamber
d) Sedimentation chamber

View Answer

Answer: b [Reason:] C represents the digested chamber. It is placed in the lower section of Imhoff tank.

2. In which of the following, the settling of solids takes place?
a) Outlet
b) Digestion chamber
c) Gas chamber
d) Sedimentation chamber

View Answer

Answer: d [Reason:] The settling of solids takes place at sedimentation chamber. It is represented by D in the above figure.

3. The maximum flow through the period at D is
a) 0.3m/min
b) 0.4m/min
c) 0.8m/min
d) 0.9m/min

View Answer

Answer: a [Reason:] The maximum flow through the period at D is 0.3m/min and its design depth should be between 3 to 3.5 m.

4. The sludge is digested in which of the following?
a) Outlet
b) Sedimentation chamber
c) Gas chamber
d) Digestion chamber

View Answer

Answer: d [Reason:] The sludge is digested in digestion chamber. Its minimum design capacity is 57 liters per person.

5. The gas chamber in the above figure is represented by
a) A
b) E
c) B
d) C

View Answer

Answer: b [Reason:] The gas chamber is represented by the E in the figure. It is located at the sides of the Imhoff tank.

6. The sewage comes in the Imhoff tank through which of the following?
a) A
b) B
c) C
d) D

View Answer

Answer: a [Reason:] A represents the inlet through which the sewage enters the Imhoff tank.

7. The detention period of the sedimentation chamber of an Imhoff tank is
a) 30 seconds
b) 30 minute
c) 1 hour
d) 2 hour

View Answer

Answer: d [Reason:] The detention period of the sedimentation chamber of an Imhoff tank is 2 hours. It is represented by D as shown in figure.

8. B in the above figure is represented by
a) Outlet
b) Sedimentation chamber
c) Gas chamber
d) Digestion chamber

View Answer

Answer: a [Reason:] B represents the outlet of Imhoff tank. It carries the partially treated sewage.

9. Which of the following is called as scum chamber?
a) Settling chamber
b) Sedimentation chamber
c) Gas chamber
d) Digestion chamber

View Answer

Answer: c [Reason:] Gas chamber is also called as scum chamber. The minimum design width of the gas chamber is 60cm.