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# Multiple choice question for engineering

## Set 1

1. In which method of population forecasting, increase in population from decade to decade is assumed constant?
a) Arithmetical increase method
b) Geometrical increase method
c) Incremental increase method
d) Decreased rate of growth method

Answer: a [Reason:] In the arithmetic increase method, Dp/dt = K where Dp/dt = rate of change of population and K is a constant. So, the increase in the population from decade to decade is assumed constant.

2. What is the expression used for population forecasting by the arithmetical increase method?
a) PO (1 + R/100)n
b) PO + n*x
c) PO + n*x + ( n(n+1)/2 )*y
d) PO – n*x

Answer: b [Reason:] The expression of the arithmetical increase method is given by PO+n*x, where PO is the present population, x is the average of the population increase in known decade and n is the number of decades.

3. In which method of population forecast, percentage increase in population from decade to decade is assumed constant?
a) Arithmetical increase method
b) Geometrical increase method
c) Incremental increase method
d) Decreased rate of growth method

Answer: b [Reason:] In the geometrical increase method, percentage increase in population from decade to decade is assumed constant. Percentage increase in population is found from a population of 3 or 4 decades and then its average is found.

4. What is the expression used for population forecasting by the geometrical increase method?
a) PO (1 + R/100)n
b) PO + n*x
c) PO + n*x + (n (n+1) /2 ) *y
d) PO – n*x

Answer: a [Reason:] The expression of geometrical increase method is given by PO (1 + R/100) n where PO is the present population, R is the average percentage growth rate per decade and n is the number of decades.

5. Which method of population forecast combines both arithmetical increase and geometrical increase method?
a) Arithmetical increase method
b) Geometrical increase method
c) Incremental increase method
d) Decreased rate of growth method

Answer: c [Reason:] In the incremental increase method, the population for the next decade is found by adding to the present population, the average increase plus the average incremental increase per decade, hence combines both arithmetical and geometrical methods.

6. What is the expression used for population forecasting by the incremental increase method?
a) PO (1 + R/100)n
b) PO + n*x
c) PO + n*x + (n (n+1) /2 ) *y
d) PO – n*x

Answer: c [Reason:] The expression of the incremental increase method is given by PO + n*x + (n (n+1) /2) *y where PO is the present population, x is the average of the population increase in known decade, y is the average of incremental increase and n is the number of decades.

7. Logistic method is also called as _______
a) Arithmetical increase method
b) Geometrical increase method
c) Incremental increase method
d) Decreased rate of growth method

Answer: d [Reason:] Logistic method is also called a decreased rate of growth method. In this method, the percentage increase in growth rate and then the percentage decrease in growth rate are founded where all populations grow according to the logistic curve.

8. Consider the following statements
1. The arithmetical increase method is suitable for new cities
2. The decreasing growth rate method is used where the rate of growth shows a downward pattern
3. The geometrical increase method is used for older cities
Which of the following above statements is/are correct?
a) 1,2,3
b) 1 and 3
c) Only 2
d) 2 and 3

Answer: c [Reason:] Arithmetical increase method is suitable for older cities, whereas a geometrical increase method is suitable for new cities.

9. Which method is suitable if the growth rate is decreasing and population is reaching towards saturation?
a) Arithmetical increase method
b) Graphical comparison method
c) Zoning method
d) Decreased rate of growth method

Answer: d [Reason:] In decreased rate of growth method, growth rate is decreasing and population is reaching towards saturation and is only valid when growth rate shows a downward pattern.

10. Which method of population forecast is suitable when extension is required for small duration and past record is available for long duration?
a) Graphical comparison method
b) Graphical extension method
c) Logistic curve method
d) Zoning method

Answer: b [Reason:] In the graphical extension method, a curve is drawn between population and time up to the present period, then the curve is extended from present to the future decade and the population is approximately determined from the extended part of the curve.

## Set 2

1. The runoff in cumec by the Rational method is defined by
a) Q = K*A*I*R
b) Q = (K+A+I) *R
c) Q = (K+A) *R
d) Q = A*I*R

Answer: a [Reason:] According to the Rational method, the storm water or runoff is defined by Q = K*A*I*R where, ‘K’ is a constant, ‘A’ is the catchment area in hectares,’I’ is the impermeability factor and ‘R’ is the intensity of rainfall in mm per hour.

2. The value of the factor K in finding the storm water flow by Rational method is
a) 100
b) 160
c) 1
d) 1/360

Answer: d [Reason:] According to the Rational method, the storm water or runoff is defined by Q = K*A*I*R where, K is a constant and K =1/360, So, Q = A*I*R/360.

3. _______ is defined as the percentage of rain water in the form of runoff.
a) Storm water flow
b) Coefficient of permeability
c) Impermeability factor
d) Coefficient of consolidation

Answer: c [Reason:] Impermeability factor is defined as the percentage of rain water in the form of runoff. The storm water flow depends on the imperviousness of the surface and if it is more, more runoff takes place.

4. The impermeability factor is also called as
a) Coefficient of impermeability
b) Runoff coefficient
c) Coefficient of permeability
d) Precipitation factor

Answer: b [Reason:] The impermeability factor is also called as runoff coefficient and it includes Kuichling’s impermeability factor and Fruhlings factor.

5. Which of the following surface has a maximum Kuichling’s impermeability factor?
b) Water tight roof surface
c) Unpaved surface

Answer: b [Reason:] The water tight roof surface has maximum Kuichling’s impermeability factor with a magnitude of 0.7 to 0.95 while gravel road, unpaved surface and macadamized road ways have <0.7.

6. Which of the following locality has a minimum Fruhlings factor?
b) An area closely built up
c) Area with 50% attached and detached houses
d) Extremely suburban area

Answer: d [Reason:] Extremely suburban area having 20% to 60/5 parking and widely detached houses has a minimum Fruhlings factor with a magnitude of 0.35 while business area, closely built up area and area with 50% attached and detached house have magnitude >0.35.

7. If the type of surface is of the most densely populated portion of the city, what is the value of Kuichling’s impermeability factor?
a) 0.14
b) 0.30
c) 0.80
d) 0.45

Answer: c [Reason:] The value of Kuichling’s impermeability factor for a surface of the most densely populated portion of the city lies between 0.7 to 0.9.

8. The value of Fruhlings factor for suburban locality is ______
a) 0.10
b) 0.20
c) 0.50
d) 0.80

Answer: c [Reason:] If the type of locality is suburban area having detached houses, the value of Fruhlings factor lies in the range of 0.45 to 0.55.

9. The storm frequency for a peripheral residential area is ___ a year.
a) Once
b) Twice
c) Thrice
d) 4 times

Answer: b [Reason:] The frequency of storm for which the sewer is to be designed for a peripheral residential area is twice a year.

10. The storm frequency for a peripheral commercial area is
a) Once a year
b) Twice a year
c) Once in 2 years
d) Once in a month

Answer: c [Reason:] The commercial and higher priced area more subject to less storm frequency than the residential area and its storm frequency is once in 2 years.

11. Shorter the duration of rainfall, ____ will be the rainfall intensity.
a) Lesser
b) Constant
c) Slightly lesser
d) Greater

Answer: d [Reason:] The intensity of rainfall is inversely proportional to the duration period, so the shorter the duration of rainfall, greater will be the rainfall intensity.

12. When the storm occurs once a year, the rainfall intensity R is
a) R = 300/ t 0.625
b) R = 150/ t 0.625
c) R = 150/ t 2
d) R = 300/ t 2

Answer: b [Reason:] When the storm occurs once a year, the rainfall intensity R is given by R = 150/ t 0.625 Where, t is the duration of storm in minutes.

13. The Kuichlings formula when the storm occurs once in 10 years is
a) R = 2667/ (t + 50)
b) R = 260/ (t + 20)
c) R = 2667/ (t + 20)
d) R = 260/ t

Answer: c [Reason:] According to Kuichling, when the storm occurs once in 10 years, the rainfall intensity R is given by R = 260/ (t + 20) and when it occurs once in 15 years, it is given by R = 3048/ (t + 20) where t is the duration of storm in minutes.

14. ________ is the time required by flood discharge to reach the maximum limit.
a) Storm frequency
b) Run-off time
c) Detention period
d) Time of concentration

Answer: d [Reason:] The time of concentration is defined as the longest time required for a drop of water to flow from the farthest point of drainage area to the point of concentration.

15. State whether the following statement is true of false.
The maximum runoff occurs when the duration of storm equals the time of concentration.
a) True
b) False

Answer: a [Reason:] It is because if duration of storm is shorter than time of concentration, then whole catchment will not be the contributing water, resulting in lesser runoff whereas if duration of storm exceeds the time of concentration, then rainfall intensity will be less, resulting in lesser runoff.

## Set 3

1. Which of the following is called as depressed sewer?
a) Lateral sewer
b) Outfall sewer
c) Inverted siphon
d) Main sewer

Answer: c [Reason:] Inverted siphon is also caused as depressed sewer as the pipes between the inlet and the outlet chamber is depressed due to obstruction like roads, bridges etc.

2. The sewage in inverted siphon will flow under
a) Air
b) Vacuum
c) Pressure
d) Gravity

Answer: c [Reason:] The sewage in inverted siphon will flow under pressure greater than the atmospheric pressure and it will not flow under gravity.

3. The design self cleansing velocity of an inverted siphon is
a) 0.9m/Sec
b) 0.6m/Sec
c) 0.7m/Sec
d) 0.4m/Sec

Answer: a [Reason:] The design self cleansing velocity of an inverted siphon is 0.9m/Sec for caring minimum, maximum and combined sanitary sewage.

4. The minimum diameter of an inverted siphon is
a) 5cm
b) 10cm
c) 15cm
d) 25cm

Answer: c [Reason:] The inverted siphon has a minimum diameter of 15cm and it is made of siphon tubes.

5. Which sewer appurtenance discharges the excess sewage flow to relief sewer?
a) Flushing tank
b) Drop manhole
c) Lamp hole
d) Storm regulators

Answer: d [Reason:] Storm regulators prevents the overloading of sewage treatment plants by discharging the excess sewage flow into relief sewer.

6. Storm regulators are classified into how many types?
a) 2
b) 3
c) 4
d) 6

Answer: b [Reason:] Storm regulator is classified into 3 types, namely Overflow weir, Siphon spillway and Leap weir.

7. Which of the following is most effective in preventing the overloading of treatment plants?
a) Street inlets
b) Overflow weir
c) Siphon valley
d) Leap weir

Answer: b [Reason:] In Siphon valley, the siphonic action takes place when the sewage quantity in combined sewer exceeds the fixed level and it get stopped as soon as it falls below that fixed level.

8. Which of the following is called a sewage ejector pump?
a) Solid handling pump
b) Air lift pump
c) Diaphragm pump
d) Reciprocating pump

Answer: a [Reason:] Solid handling pump is also called as sewage ejector pump where pumping of raw sewage takes place which are mostly in solid form.

9. Which of the following pump is used for removal of grit?
a) Centrifugal pump
b) Pneumatic ejector
c) Rotary screw pump
d) Air lift pump

Answer: c [Reason:] At Rotary screw pump, the motor rotates on a shaft to lift the solid waste material to a higher level and they are used in grit chambers for removing grit.

10. State whether the following statement is true or false.
The septic tank and pump chamber should be kept as deep as possible.
a) True
b) False

Answer: b [Reason:] The septic tank and pump chamber should be placed at shallow depth as it will result in easier inspection, repairment and maintenance of them.

11. Which part of pump chamber allows to easily disconnect from the pipeline?
a) Gate valve
b) Check valve
c) Union
d) Pump lift chain

Answer: c [Reason:] Union is a device which is placed in the pump discharge pipe that allows the pump to easily disconnect from the pipe in the pump chamber.

12. Which device warns that the liquid is above the pump level?
a) High level alarm
b) Check valve
c) Union
d) Pump lift chain

Answer: a [Reason:] High level alarms give a red light as a warning signal that warns the user that wastewater is above the pump level.

13. Which of the following device prevents the back flow of wastewater?
a) Gate valve
b) Check valve
c) Union
d) Pump lift chain

Answer: b [Reason:] Check valve allows the flow of wastewater in one direction and prevents the back flow of water.

14. Which component of the pumping chamber prevents ground water from entering the septic tank?
a) Pump lift chain
b) Access riser
c) Check valve
d) Union

Answer: b [Reason:] Access riser are large diameter riser with 61cm diameter that prevents the ground and surface water from entering the septic tank.

15. Which of the following represents the correct order in terms of maximum efficiency of the pump?
a) Centrifugal > Airlift > Diaphragm
b) Diaphragm > Airlift > Centrifugal
c) Airlift > Centrifugal > Diaphragm
d) Centrifugal > Diaphragm > Airlift

Answer: d [Reason:] The maximum efficiency of centrifugal pump is 85%, while of Diaphragm and Airlift pumps are 30% and less than 25% respectively.

## Set 4

1. Which process of water treatment is done to avoid floating debris, branches, trees or other large particles suspended in water?
a) Screening
b) Aeration
c) Primary sedimentation
d) Secondary sedimentation

Answer: a [Reason:] Screens are used as a pretreatment process for purification of water to avoid large size suspended materials from water.

2. What is the size of coarse screen used in pretreatment of water?
a) 25mm
b) 50mm
c) 75mm
d) 100mm

Answer: a [Reason:] Coarse screens are used in the form of bars of 25mm diameter size and are spaced at 75 to 100mm centers.

3. The coarse screen is inclined at _____ to facilitate the cleaning or raking.
a) 300
b) 350
c) 450
d) 900

Answer: c [Reason:] The coarse screen is inclined at 450-600 so that they can be easily cleaned with a rake. Moreover, it reduces the flow velocity which also helps in cleaning the screen.

4. The head loss through screen depends on
a) Shape of screen elements
b) Open area, block area
c) Approach velocity
d) Nature of their construction, approach velocity

Answer: d [Reason:] The head loss through the screen is given by, h=B (w/b) 4/3h1*sinx Where h=head loss, h1=approach velocity head, b=minimum width, x=angle of rack, B=shape factor. It also depends on the nature of their construction.

5. The shape factor for circular rods in finding the head loss through the screen is _____
a) 1.79
b) 2.42
c) 1.83
d) 1.45

Answer: a [Reason:] The shape factor rectangular bar with sharp edges is 2.42, for semicircular face is 1.83 and for circular rod is 1.79.

6. State whether the following statement is True or False.
Micro strainers are used to remove color in water.
a) True
b) False

Answer: b [Reason:] Micro strainers are used for screening stored water which contains plankton, algae and other microscopic particles.

7. Identify the incorrect statement regarding aeration process.
a) It removes taste and odor
b) It increases the dissolved oxygen content of water
c) It increases the carbon dioxide content of water
d) It is used for mixing chemicals with water

Answer: c [Reason:] Aeration reduces the carbon dioxide content and corrosiveness of water and hence, raises the pH value of water.

8. The reduction of carbon dioxide by cascade aerators is in the range of
a) 10-20%
b) 20-30%
c) 40-50%
d) 50-60%

Answer: d [Reason:] Cascade aerators are the gravity aerators in which water falls from 1-3m height such that it comes in contact with air and reduces carbon dioxide content to 50-60%.

9. In which type of aerator, the flow of water is divided into fine streams and small droplets?
b) Inclined apron aerator
c) Spray aerator
d) Gravel bed aerator

Answer: a [Reason:] In Cascade aerator, the flow of water is divided into fine streams and small droplets such that they come in contact with air in their trajectories and reduces CO2 by 70-90%.

10. The elapsed time in gravity filter is 1sec. What is the height of fall in a single descent?
a) 4.4m
b) 4.9m
c) 8.8m
d) 9.8m

Answer: b [Reason:] t = 1sec, g = 9.8 Elapsed time, t = (2h/g) 1/2 in a single descent. Height of fall, H = t2g/2 = 1*1*9.8/2= 4.9m.

11. ______ are used in fine screen so that they do not get clogged up.
a) Automatic strainers
b) Spray aerators
d) Gravel bed aerators

Answer: a [Reason:] Automatic strainers are self cleaning devices which remove solids from the flowing liquid continuously and help in fine screen so that it do not get clogged up.

## Set 5

1. Which type of sewer serves as an outlet for large territory?
a) Lateral sewer
b) Main sewer
c) Branch sewer
d) Separate sewer

Answer: b [Reason:] Main sewer acts as an outlet for the large territory as it receives sewage from many tributary branches.

2. Which sewer collects sewage directly from the house?
a) Main sewer
b) Outfall sewer
c) Lateral sewer
d) Intercepting sewer

Answer: c [Reason:] The first stage of collection of sewage starts from the house which is done by Lateral sewer.

3. _______ sewer collects sewage from collecting system to a disposal plant?
a) House sewer
b) Outfall sewer
c) Lateral sewer
d) Separate sewer

Answer: b [Reason:] The Outfall sewer is a sewer which carries the sewage from collecting systems and transfers it to a point of final discharge i.e a disposal plant.

4. Which sewer carries both sewage and storm water?
a) Outfall sewer
b) Separate sewer
c) Main sewer
d) Combined sewer

Answer: d [Reason:] Combined sewer carries both the sewage and the rain water from the roofs of the house and from the street.

5. Which sewer is also called as submain sewer?
a) Branch sewer
b) Separate sewer
c) Main sewer
d) Lateral sewer

Answer: a [Reason:] Submain sewer receives sewage from small area which finally get discharged into the main sewer.It is also called as branch sewer.

6. Which sewer is used to carry the excess flow of existing sewer?
a) Branch sewer
b) Relief sewer
c) Main sewer
d) Lateral sewer

Answer: a [Reason:] The Relief sewer is used to carry the excess flow of existing sewer. It is also called as overflow sewer.

7.Asbestos cement sewers are made from
a) Cement, silica
b) Asbestos fibre, copper
c) Asbestos fibre, cement, silica
d) Asbestos fibre, magnesium

Answer: c [Reason:] Asbestos cement sewers are made from the composition of asbestos fibre, cement, silica asbestos fibre acts as a reinforcing material.

8.Which of the following is a disadvantage of asbestos cement sewer?
a) They are light weight
b) They can be easily jointed
c) They are brittle
d) Inside surface is smooth