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Multiple choice question for engineering

Set 1

1. Which system of collection of sewage is a dry system?
a) Conservancy system
b) Biological digestion
c) Incernation
d) Water carriage system

View Answer

Answer: a [Reason:] The conservancy system is a dry and old system where sewage is deposited in the pit and then removed periodically after 24 hours.

2. After how many years, night soil gives good quality manure?
a) 1
b) 5
c) 10
d) 14

View Answer

Answer: a [Reason:] Night soil is buried into the ground or trenches to give good quality manure in 1 or 2 years.

3. Hog feeding is a type of ______
a) Campaign
b) Food contest
c) Garbage disposal method
d) Disease

View Answer

Answer: c [Reason:] Hog feeding is a type of garbage disposal method where hog eats the garbage. However, this method is opposed by health official as the place where hogs are kept smelling very bad.

4. State whether the following statement is true or false.
Conservancy system is a highly unhygienic system, causing insanitary conditions.
a) True
b) False

View Answer

Answer: a [Reason:] In conservancy system, the excreta starts decomposing within the few hours of its production, produce bad smell and give rise to fly nuisance.

5. Which of the following is not correct regarding conservancy system?
a) High maintenance cost
b) Highly unhygienic system
c) Independent of labour
d) Chances of epidemic

View Answer

Answer: c [Reason:] This system is highly dependent on labour. Absence of Labour even for a day will cause a foul smell in the whole area.

6. Which system of collection of sewage is called a dry system?
a) Conservancy system
b) Biological digestion
c) Incernation
d) Water carriage system

View Answer

Answer: a [Reason:] The conservancy system is an old method of collection of sewage where instead of water; humans are responsible for its collection, conveyance and disposal.

7. ________ is a method where water is used as a medium for the flow of sewage from its production of the treatment unit.
a) Conservancy system
b) Biological digestion
c) Incernation
d) Water carriage system

View Answer

Answer: d [Reason:] In water carriage system, the collection, conveyance and disposal of various types of wastes are carried out with the help of water.

8. Normally, the amount of water required for flushing operation is _____ litres.
a) 10-20
b) 5-10
c) 15-20
d) 20-30

View Answer

Answer: b [Reason:] In water carriage system, water closets are used where human excreta is removed by the flushing 5-10 litres of water by each person.

9. State whether the following statement is true or false.
The water carriage system is a hygienic system without any bad smell.
a) True
b) False

View Answer

Answer: a [Reason:] Water carriage system is very hygienic as the night soil and other waste water is conveyed through close conduits which are not directly exposed to the atmosphere.

10. Which of the following is correct regarding water carriage system?
a) Chances of the epidemic is there
b) Foul smell is produced
c) Does not cause pollution
d) Highly dependent on labours

View Answer

Answer: c [Reason:] The liquid waste in the water carriage system is directly conveyed through the sewer, so there is no chance of the waste being soaked into the ground or contaminating the soil.

Set 2

1. Which of the following is not a sewer appurtenance?
a) Storm regulator
b) Flushing tank
c) Water tank
d) Manholes

View Answer

Answer: c [Reason:] Sewer appurtenance are the structures which are constructed for the efficient performance and maintenance of sewers. The water tank is not a sewer appurtenance.

2. ______ provides the working space for maintenance and inspection of sewers.
a) Lamp holes
b) Manholes
c) Flushing tanks
d) Working chamber

View Answer

Answer: d [Reason:] Working chamber provides the working space for maintenance and inspection of sewers. It is situated at the lower part of the manhole.

3. The minimum thickness of the side wall of the manhole is
a) 50mm
b) 100mm
c) 225mm
d) 300mm

View Answer

Answer: c [Reason:] The minimum thickness of the side wall of the manhole is 225mm and they are commonly made of bricks.

4. Which of the following is situated above the working chamber in a deep manhole?
a) Main sewer
b) Access shaft
c) Branch sewer
d) Channel

View Answer

Answer: b [Reason:] The access shaft lies above the working chamber which is just below the manhole cover.

5. If the depth of excavation is 4m. What is the thickness of the brick wall of manhole?
a) 12cm
b) 16cm
c) 20cm
d) 26cm

View Answer

Answer: d [Reason:] The thickness of brick wall of manhole (in cm) = 10 + 4*depth of excavation (in m) = 10 + 4*4 = 26cm.

6. Into how many types manholes are classified on the basis of depth of manhole?
a) 3
b) 5
c) 6
d) 7

View Answer

Answer: a [Reason:] Manholes are classified into Shallow, Normal and Deep on the basis of depth of the manhole.

7. The minimum diameter of the access shaft for a circular manhole is
a) 60cm
b) 20cm
c) 30cm
d) 10cm

View Answer

Answer: a [Reason:] Access shaft is the upper portion of manhole whose minimum diameter for a circular manhole is 60cm.

8. The manhole in which inclined pipe for transfer of sewage from branch to main sewer is
a) Deep manhole
b) Ramp
c) Drop manhole
d) Normal manhole

View Answer

Answer: b [Reason:] Ramp has an inclined pipe for the transfer of sewage which is used when the drop is less.

9. The thickness of the manhole frame is
a) 10cm
b) 15cm
c) 20cm
d) 40cm

View Answer

Answer: c [Reason:] The manhole frame is made of cast iron having 10cm width and the thickness is 20cm.

10. The minimum diameter of working chamber for a circular manhole is
a) 0.8m
b) 0.9m
c) 1m
d) 1.2m

View Answer

Answer: d [Reason:] The working chamber is the lower portion of the manhole having a minimum diameter of 1.2 m.

11. The manhole in which vertical pipe is used for the transfer of sewage from branch to main sewer is
a) Deep manhole
b) Ramp
c) Drop manhole
d) Normal manhole

View Answer

Answer: c [Reason:] Drop manholes are provided with vertical pipe so that the sewage does not fall on the people working at manhole.

12. Which sewer appurtenance allows lamp in the sewer?
a) Catch basin
b) Drop manhole
c) Lamp hole
d) Storm regulators

View Answer

Answer: c [Reason:] The lamp hole is acting as an inspection device where lamps are inserted.It is used when the construction of manhole is difficult.

13. Which sewer appurtenance is used for removing rainwater from the roads?
a) Catch basin
b) Gullies
c) Lamp hole
d) Storm regulators

View Answer

Answer: b [Reason:] Gullies are placed along the roadside at an interval of 30-60m to remove the rainwater from the road.

14. ________ removes oil and grease from the sewage.
a) Catch basin
b) Gullies
c) Grease and oil traps
d) Storm regulators

View Answer

Answer: c [Reason:] The oil and grease sticks to the sides of the sewer and reduce the sewer capacity. So, it is essential to remove oil and grease, which can be done by the device called as Grease and oil traps.

15. Which device is used to prevent the clogging of sewer pipes?
a) Flushing tank
b) Drop manhole
c) Lamp hole
d) Storm regulators

View Answer

Answer: a [Reason:] Flushing tank is used to flush and clean the sewer to prevent it from clogging. This is done either by automatic flushing tank or by hand operated flushing tank.

Set 3

1. Which of the following is a prime lake pollutant.
a) Iodine
b) Phosphorous
c) Potassium
d) Sodium

View Answer

Answer: b [Reason:] Phosphorous is a prime lake pollutant that promotes the algal bloom and destroys the quality and appearance of a lake.

2. State whether the following statement is true or false.
The turbulence decreases the DO content of water.
a) True
b) False

View Answer

Answer: b [Reason:] The turbulence increases the DO content of water, however, beyond a certain limit, it scours the sediments placed at the bottom.

3. The dilution factor is expressed by
a) Volume of diluted sample + Volume of sewage
b) Volume of diluted sample / Volume of sewage
c) Volume of diluted sample – Volume of sewage
d) Volume of diluted sample* Volume of sewage

View Answer

Answer: b [Reason:] The dilution factor is the ratio of volume of diluted sample of water to the volume of sewage. It is used in finding the BOD of water.

4. The tolerance limit of BOD of sewage to be disposed on land is
a) 100ppm
b) 200ppm
c) 500ppm
d) 400ppm

View Answer

Answer: c [Reason:] The tolerance limit of BOD of sewage to be discharged into sea water is 100ppm while to be disposed on land is 500ppm.

5. The tolerance limit of pH value of sewage to be discharged into sea water is
a) 1-5ppm
b) 2-9ppm
c) 5.5-9ppm
d) 6-10ppm

View Answer

Answer: c [Reason:] The tolerance limit of pH value of sewage to be discharged into sea water or to be disposed on land is between 5.5 and 9ppm.

6. The dilution factor is 400. What should be the type of treatment given to the water?
a) Preliminary treatment
b) Sedimentation, Flocculation
c) Complete treatment
d) No treatment

View Answer

Answer: a [Reason:] When the dilution factor lies between 300 and 500, then preliminary treatment is given to the water.

7. The tolerance limit of oil and grease of sewage to be disposed on land is
a) 40ppm
b) 30ppm
c) 20ppm
d) 10ppm

View Answer

Answer:b [Reason:] The tolerance limit of oil and grease of sewage to be disposed on land is 30ppm while on sea water is 20ppm.

8. The minimum depth to which sewage should be discharged of sea water is
a) 0.5m
b) 1m
c) 2m
d) 3m

View Answer

Answer: d [Reason:] The minimum depth to which sewage should be discharged of sea water is 3m to avoid marine pollution.

9. The tolerance limit of COD of sewage to be discharged in sea water is
a) 250ppm
b) 100ppm
c) 40ppm
d) 20ppm

View Answer

Answer: a [Reason:] The tolerance limit of COD of sewage to be discharged in sea water and on land for irrigation purpose is 250ppm.

Set 4

1. _________ is the flow through sewers available during non-rainfall period.
a) Gradually varied flow
b) Rapidly varied flow
c) Dry weather flow
d) Storm water flow

View Answer

Answer: c [Reason:] Dry weather flow is the flow through sewers available during non-rainfall period. It consists of domestic sewage and waste water sewage.

2. _______ is the additional flow occurring during rainy season.
a) Gradually varied flow
b) Rapidly varied flow
c) Dry weather flow
d) Storm water flow

View Answer

Answer: d [Reason:] The storm water flow is the additional flow occurring during the rainy season. It consists of runoff from roofs, streets or open spaces during rainfall.

3. Which flow is also called as sanitary sewage?
a) Dry weather flow
b) Storm weather flow
c) Uniform flow
d) Non uniform flow

View Answer

Answer: a [Reason:] Dry weather flow is the quantity of wastewater that flows through a sewer in dry weather when no storm water is present in the sewer.

4. Which of the following factor does not effect the dry weather flow?
a) Rate of water supply
b) Temperature conditions
c) Population growth
d) Infiltration of ground water

View Answer

Answer: b [Reason:] There are four factors that affect the dry weather flow, namely the rate of water supply, population growth, type of area served and infiltration of ground water.

5. The quantity of waste water is assumed to be ___ % of the quantity of water supply.
a) 40
b) 50
c) 60
d) 80

View Answer

Answer: d [Reason:] The quantity of waste water is assumed to be 80 % of the quantity of water supply when no extra water enters the sewer.

6. The sewer should be designed for a minimum of ______ litres of waste water per capita per day.
a) 50
b) 100
c) 150
d) 1000

View Answer

Answer: c [Reason:] Sewer is an underground carriage system that takes impure water from houses and commercial buildings through pipes to treatment units and they should be designed for a minimum of 150 litres of waste water per capita per day.

7. The size of the town is 15,000. What is the density of population per hectare?
a) 50
b) 75
c) 100
d) 200

View Answer

Answer: d [Reason:] When the size of the town is between 5000 and 20,000, the density of population per hectare is between 150 and 200.

8. The design period of main and branch sewer is
a) 5years
b) 10years
c) 30years
d) 40years

View Answer

Answer: c [Reason:] The main and branch sewer is designed for the population that may occur at the end of one generation of 30 years.This period of 30 years is called design period.

9. ___________ is the process in which ground water unfiltrate into the sewers.
a) Exfiltration
b) Infiltration
c) Filtration
d) Osmosis

View Answer

Answer: b [Reason:] Infiltration is the process in which ground water unfiltrate into the sewers. It increases the load on the treatment work.

10. ________ is the process which indicates the flow of waste water from the sewer into the ground.
a) Exfiltration
b) Infiltration
c) Filtration
d) Osmosis

View Answer

Answer: a [Reason:] Exfiltration is the reverse process of Infiltration where flow through sewer decreases and pollution of the ground water increases.

11. Infiltration of water does not depend on
a) Size of sewer
b) Sewer material
c) Quality of water
d) Type of soil

View Answer

Answer: c [Reason:] The infiltration of water depends on depth of sewer below ground water, size and length of sewer, sewer material, type of joints, nature and type of soil through which sewer is laid.

12. The rate of infiltration lies in the range of ______ m3/hectare/day.
a) 0.20-0.28
b) 0.42-0.63
c) 0.60-0.80
d) 0.70-0.90

View Answer

Answer: a [Reason:] The rate of infiltration is expressed as litres per hectare of area per day. The rate of infiltration lies in the range of 0.2-0.28m3/hectare/day.

13. The relation between the maximum and average rate of flow is defined by
a) QMAX = (1 + 14/(4 + P0.5)) * QAVG
b) QMAX = (1 + 1/(4 + P0.5)) * QAVG
c) QMAX = (1 + 4 + P0.5) * QAVG
d) QMAX = (1 + P0.5) * QAVG

View Answer

Answer: a [Reason:] According to Harmon’s formula, the maximum and the average rate of flow is defined by QMAX = (1 + 14/(4 + P0.5)) * QAVG where P is the population in thousands.

Set 5

1. The average standard BOD of domestic sewage is measured in
a) ppm
b) Kg/day
c) Kg per person per day
d) Number of persons per day

View Answer

Answer: c [Reason:] The average standard BOD of domestic sewage is measured in 0.08Kg per person per day.

2. Which of the following id the correct expression of population equivalent?
a) BOD of industrial sewage in kg/day * 0.08
b) 0.08 * BOD of industrial sewage kg/day
c) BOD of industrial sewage kg/day / 0.08kg/person/day
d) BOD of industrial sewage kg/day +0.08

View Answer

Answer: c [Reason:] BOD of industrial sewage kg/day /(0.08kg/person/day) where 0.08 represents the average standard BOD of domestic sewage.

3. The expression of relative stability at 20oC is given by
a) S = (1-(0.794)T20
b) S = 100 (1-(0.794) T20)
c) S = 1-(0.794) T20
d) S = 100 (0.794) T20

View Answer

Answer: b [Reason:] The expression of relative stability at 20oC is given by S=100 (1-(0.794)T20) where T20 represents the incubation period at 20oC.

4. The expression of relative stability at 37oC is given by
a) S = (1-(0.794)T37
b) S = 100 (1-(0.794) T37)
c) S = 1-(0.794) T20
d) S = 100 (1-(0.630)T37)

View Answer

Answer: d [Reason:] The expression of relative stability at 37oC is given by S = 100 (1-(0.630) T37) where T37 represents the incubation period at 37oC.

5. What is the value of BOD of industrial sewage in kg/day, given population equivalent as 6000 persons?
a) 480
b) 160
c) 270
d) 100

View Answer

Answer: a [Reason:] BOD of industrial sewage in kg/day = Population equivalent * Average standard BOD of domestic sewage = 6000*0.08 = 480kg/day.

6. Calculate the percentage of relative stability, given 5 day incubation period at 370C.
a) 50%
b) 60%
c) 90%
d) 99%

View Answer

Answer: c [Reason:] Relative stability at 370C is given by, S = 100 (1-(0.630) T37) = 100 (1-(0.630)5) = 90.08% which is approximately 90%.

7. _____ is the amount of oxygen required to oxidize both organic and inorganic matter in sewage.
a) Turbidity
b) BOD
c) COD
d) DO

View Answer

Answer: c [Reason:] COD is the amount of oxygen required to oxidize both organic and inorganic matter in sewage. It is always greater than BOD.

8. COD is abbreviated as
a) Chemical oxygen demand
b) Complex oxygen demand
c) Customary oxygen demand
d) Chemical oxygen deficit

View Answer

Answer: a [Reason:] COD is abbreviated as chemical oxygen demand. It is measured in ppm or mg/L.

9. The oxidizing agent used in COD test is
a) Potassium chloride
b) Potassium per-manganate
c) Potassium chromate
d) Potassium dichromate

View Answer

Answer: d [Reason:] In COD test, oxidization of organic matter takes place by potassium dichromate in the presence of sulphuric acid using ferroin as indicator.

10. 5 days BOD at 20oC is ___ of total demand.
a) 20%
b) 47%
c) 68%
d) 100%

View Answer

Answer: c [Reason:] 5 days BOD at 20oC is the standard BOD which is 68% of total demand, whereas 10 days BOD at 20oC is 90% of total demand.

11. Which of the following expression is correct regarding deoxygenation constant where symbols have their usual meaning?
a) KDT = KD20 + (1.047)T-20
b) KDT = KD20 / (1.047) T-20
c) KDT = KD20 (1.047) T-20
d) KDT = KD20 (1.04T

View Answer

Answer: c [Reason:] KDT = KD20 (1.047) T-20 where, KDT is the deoxygenation constant at temperature ‘T’ and KD20 is the deoxygenation constant at 20oC.

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