Multiple choice question for engineering
Set 1
1. Which of the following sewer is called as ovoid sewer?
a) Asbestos cement sewer
b) Egg shaped sewer
c) Plain cement sewer
d) Salt glazed sewer
Answer
Answer: b [Reason:] Egg shaped sewer is an oval shaped sewer and is also called as ovoid sewer.
2. State whether the following statement is true of false.
Egg shaped sewers are more suitable in a combined system during dry weather flow.
a) True
b) False
Answer
Answer: b [Reason:] Egg shaped sewers are more suitable in a combined system during maximum rain water flow as for low flows, they give sufficient velocity.
3. Which of the following is incorrect regarding Egg shaped sewer?
a) It is cheap
b) It is difficult to construct
c) It is less stable
d) It is mainly circular in shape
Answer
Answer: a [Reason:] The Egg shaped sewer is expensive as more material is required than other sewer. Moreover, the cost of construction is high.
4. The upper portion of Egg shaped sewer is called as _____
a) Level
b) Arch
c) Invert
d) Wedge
Answer
Answer: b [Reason:] The upper portion of Egg shaped sewer is called as arch which is circular in shape and is larger than the lower circular section.
5. The Egg shaped sewer provides ____ velocity for low flows over the circular sewer of equal capacity.
a) Lesser
b) Higher
c) Slightly higher
d) Very high
Answer
Answer: c [Reason:] The Egg shaped sewer provides slightly higher velocity for low flows over the circular sewer of equal capacity. This makes it useful during combined sewerage system.
6. The lower portion of Egg shaped sewer is known as _____
a) Roof
b) Invert
c) Arch
d) Wedge
Answer
Answer: b [Reason:] The lower portion of Egg shaped sewer is known as invert which is circular in shape and is smaller than the arch.
7. The height of standard section of Egg shaped sewer is ______ the new shaped section.
a) Equal to
b) Twice of
c) Less than
d) Half of
Answer
Answer: a [Reason:] The height of both the standard and a new shaped section of Egg shaped sewer is 3 times the radius of sewer. So, their heights are equal.
8. The ratio of the width of the standard section and new shaped section of Egg shaped section is
a) 1:2
b) 2:1
c) 1:1
d) 1:3
Answer
Answer: c [Reason:] Width of standard section= 2 times radius of sewer
Width of new shaped section = 2 times radius of sewer
So, their ratio = 1:1.
9. The radius of invert of the standard section of Egg shaped sewer is ____ of the new shaped section.
a) Twice
b) Thrice
c) Half
d) Equivalent
Answer
Answer: a [Reason:] Let k be the radius of sewer. The radius of invert of the standard section= 0.5k and the radius of invert of the new shaped section = 0.25k. So, radius of invert of the standard section is twice of the new shaped section of Ovoid sewer.
10._______ denotes the characteristic size of circular cross section of sewer.
a) DN
b) MN
c) QW
d) SE
Answer
Answer: a [Reason:] DN denotes the internal diameter of circular cross section of sewer. It is measured in mm.
11.The arch cross section is divided into how many types?
a) 2
b) 3
c) 4
d) 5
Answer
Answer: b [Reason:] The arch cross section is divided into 3 types, namely Normal, Extended and Squashed arch cross section.
12.One side walkway is a type of
a) Circular cross section
b) Channel cross section
c) Ovoid cross section
d) Arch cross section
Answer
Answer: b [Reason:] The channel cross section is divided into 2 types. It includes One side walkway and Two side walkway channel cross section.
13.Which of the following ovoid cross section has the maximum nominal size range?
a) Squashed
b) Extended
c) Normal
d) Wide
Answer
Answer: a [Reason:] Squashed ovoid cross section has the maximum nominal size range with breadth and height as 3200mm.
14.State whether the following statement is true or false.
There is less deposition of waste in ovoid cross-section.
a) True
b) False
Answer
Answer: a [Reason:] Ovoid sewer cross-section offers less deposition of waste which results in better handling of waste in sewage treatment plant during dry weather and reduced emission of waste during wet weather.
Set 2
1. The magnitude of hoop stress on sewer is given
a) PD/2t
b) PD/t
c) 2PD/t
d) PD/2
Answer
Answer: a [Reason:] The magnitude of hoop stress on sewer is given by PD/2t where, P is the internal pressure, D is the diameter of sewer and t is the thickness of the shell.
2. In order to reduce temperature stress, _____ joints are provided.
a) Contraction
b) Expansion
c) Bell and spigot
d) Collar
Answer
Answer: b [Reason:] In order to reduce temperature stress, expansion joints are provided at intervals of 20m to 30m.
3. The expression for the temperature stress is given by
a) EPαt
b) EPαt/2
c) 2EPαt
d) EP/αt
Answer
Answer: a [Reason:] The expression for the temperature stress is given by EPαt where, EP is the modulus of elasticity of pipe, α is the coefficient of thermal expansion and ‘t’ is the change in temperature.
4. The type of backfill is saturated clay. What is its unit weight?
a) 1040kg/m3
b) 2080kg/m3
c) 2000kg/m3
d) 1500kg/m3
Answer
Answer: b [Reason:] When the type of backfill is saturated clay, then its unit weight is 2080kg/m3.
5. Which of the following has the minimum unit weight?
a) Dry sand
b) Wet sand
c) Damp clay
d) Ordinary sand
Answer
Answer: a [Reason:] The unit weight of wet sand, damp clay, ordinary sand and dry sand are 1920kg/m3, 1920kg/m3, 1840kg/m3 and 1600kg/m3 respectively.
6. The type of soil is loose dry sand. What is the coefficient of cohesion of the soil?
a) 100
b) 200
c) 500
d) 0
Answer
Answer: d [Reason:] Loose dry sand is a cohesionless soil. So, the value of the coefficient of cohesion is 0.
7. Which of the following order is correct regarding coefficient of cohesion?
a) Hard clay < Dense sand > Medium clay > Soft clay
b) Hard clay > Dense sand > Medium clay > Soft clay
c) Medium clay > Dense sand > Hard clay > Soft clay
d) Dense sand > Medium clay > Hard clay > Soft clay
Answer
Answer: b [Reason:] The coefficient of cohesion of Hard clay, Dense sand, Medium clay and Soft clay are 4700kg/m2, 1400kg/m2, 1200kg/m2 and 200kg/m2 respectively.
8. How many types of underground sewer are there on the basis of construction conditions?
a) 2
b) 3
c) 4
d) 5
Answer
Answer: b [Reason:] Depending upon the type of the construction conditions, underground sewers are of 3 types, namely Trench ditch condition, Embankment condition and Tunnel condition.
9. _______ condition exist when the sewer is laid at a depth between 9m to 12m.
a) Trench ditch
b) Trench
c) Tunnel
d) Embankment
Answer
Answer: c [Reason:] Tunnel condition exists when the sewer is laid at a depth between 9m to 12m. This process is done by jacking or by tunneling.
10. Negative projecting condition is a type of ______ condition.
a) Trench ditch
b) Trench
c) Tunnel
d) Embankment
Answer
Answer: d [Reason:] Negative projecting condition exists when the trench is narrower with respect to the size of the pipe and shallow with respect to the depth of cover.
Set 3
1. Which of the following is incorrect regarding circular sewer?
a) It is easily manufactured
b) It offers more opportunities for deposits
c) It is the most economical section
d) It has uniform curvature
Answer
Answer: b [Reason:] The circular section has uniform curvature, so it offers less opportunities for deposits.
2. A circular section of sewer gives _______ area for a given perimeter.
a) Small
b) Large
c) Minimum
d) Maximum
Answer
Answer: d [Reason:] A circular section of sewer gives a maximum area for a given perimeter and give the greatest hydraulic mean depth when running full or half.
3. What is the wetted perimeter of a circular section of sewer?
a) (22/7) *D2
b) (22/7) *D
c) (22/7) *D2
d) (22/7)2 *D
Answer
Answer: b [Reason:] The wetted perimeter of a circular section of sewer running full is (22/7) *D where D is the internal diameter of circular sewer.
4. The hydraulic mean depth of a circular section running full is
a) `D
b) D/2
c) D2
d) D/4
Answer
Answer: d [Reason:] The hydraulic mean depth, R = Area of cross section / Wetted perimeter
= ((22/7) *D2/4) / (22/7) *D
= D/4.
5. The proportional depth of a circular sewer running partially half is
a) (1-cosK/2)
b) (1/2) * (1-sinK/2)
c) (1/2) * (1-cosK/2)
d) (1-cosK/2)2
Answer
Answer: c [Reason:] Depth of flow d = (D/2) * (1-cosK/2)
Proportional depth = Depth of flow d / Diameter of section D = (D/2) * (1-cosK/2) / D
= (1/2) * (1-cosK/2).
6. The proportional perimeter of a circular sewer running partially half where K is the central angle subtended at a circular section of sewer is
a) K/360o
b) K/90o
c) K/270o
d) K/180o
Answer
Answer: a [Reason:] Proportional perimeter of a circular sewer running partially half =
(22/7) *D*K/360o / ((22/7) *D) = K/360o.
7. The diameter of circular sewer is 0.2m. The desired depth of flow is
a) 2/3 of the circular section of sewer
b) 1/3 of the circular section of sewer
c) 1/2 of the circular section of sewer
d) 1/4 of the circular section of sewer
Answer
Answer: c [Reason:] When the diameter of the sewer is up to 0.4m, they are designed to flow at 1/2 depth.
8. The diameter of a circular sewer is 0.8m. The desired depth of flow is
a) 2/3 of the circular section of sewer
b) 1/3 of the circular section of sewer
c) 1/2 of the circular section of sewer
d) 1/4 of the circular section of sewer
Answer
Answer: a [Reason:] When the diameter of the sewer is between 0.4m and 0.8m, they are designed to flow at 2/3 depth.
9. A circular sewer having 0.4m diameter is flowing with velocity 2m/Sec. If the gradient of sewer is 1 in 90. Find the value of Chezy’s coefficient?
a) 10
b) 30
c) 60
d) 40
Answer
Answer: d [Reason:] Hydraulic mean depth, R= D/4 = 0.4/4 = 0.1m
Slope of sewer S = 1/100, velocity V = 1m/Sec
According to Chezy’s formula, V = C (RS) 1/2 = C* (0.1/90) 1/2 = C/30
C = V*30 = 2*30 = 60.
Set 4
1. State whether the following statement is true of false.
The flow of sewage in the sewers is independent of the its slope and geometry.
a) True
b) False
Answer
Answer: b [Reason:] The flow of sewage in the sewers depends on flow condition, characteristic of sewage, slope and geometry of sewer, bends, transitions and roughness of the interior surface of sewer.
2. The expression of the Chezy’s formula is given by
a) V = C/RS
b) V = CRS2
c) V = C (RS) 1/2
d) V = C/ (RS) 1/2
Answer
Answer: c [Reason:] Chezy’s formula is given by V = C (RS)1/2 where C is the Chezy’s constant, R is the hydraulic mean radius and S is the hydraulic gradient.
3. The value of Kutter’s coefficient for cast iron is
a) 0.02
b) 0.012
c) 0.12
d) 0.13
Answer
Answer: b [Reason:] When the condition of interior surface is good, the value of Kutter’s coefficient for cast iron is 0.012.
4. The value of manning’s coefficient for cement concrete is
a) 0.017
b) 0.13
c) 0.013
d) 0.17
Answer
Answer: c [Reason:] When the condition of interior surface is good, the value of Manning’s coefficient for cement concrete is 0.013.
5. Which of the following conduit material has the maximum Kutter’s coefficient in terms of good surface?
a) Brick
b) Salt glazed stoneware
c) Cast iron
d) Galvanized iron
Answer
Answer: a [Reason:] The unglazed brick has the maximum Kutter’s coefficient in terms of good surface with the value of 0.013.
6. The value of Bazen’s constant for good earthen channels is
a) 0.12
b) 1.54
c) 0.50
d) 3.17
Answer
Answer: c [Reason:] When the type of inside surface of sewer is a good earthen channel, the value of Bazen’s constant is 0.50.
7. Which of the following has minimum manning’s coefficient in terms of fair interior surface?
a) Plastic smooths
b) Asbestos cement
c) Brick
d) Cement concrete
Answer
Answer: a [Reason:] Plastic smooth has the minimum Manning’s coefficient in terms of fair interior surface with a value of 0.011.
8. Which of the following is the expression of the Manning’s formula?
a) V = R1/3 S1/2/ N
b) V = R2/3 S2/ N
c) V = R2/3 S1/2/ N
d) V = R2/3 S1/2
Answer
Answer: c [Reason:] The Manning’s formula is given by V = R2/3 S1/2/ N where V is the velocity of flow, ‘R’ is the mean hydraulic radius, ‘S’ is the slope of the sewer and ‘N’ is the rugosity coefficient.
9. Which of the following order is correct regarding Hazen and William’s coefficient?
1. Steel pipe
2. Cement lined pipe
3. Wood stave pipe
4. Asbestos cement pipe
a) 1 > 2 > 3 > 4
b) 1 > 3 > 2 >4
c) 4 > 2 >3 > 1
d) 4 > 3 > 2 > 1
Answer
Answer: d [Reason:] The Hazen and William’s coefficient for Asbestos cement pipe is 140 while of Steel pipe, Cement lined pipe and Wood stave pipe are 95, 110 and 120 respectively.
Set 5
1. The diameter of plain cement concrete pipes used for sewerage system is
a) 20mm
b) 30mm
c) 90mm
d) 63mm
Answer
Answer: c [Reason:] The range of diameter of plain cement concrete pipes for sewerage system is from 80mm to 450mm and its thickness varies from 25 to 35mm.
2. The grade of concrete used in plain cement concrete sewer is
a) M5
b) M10
c) M15
d) M20
Answer
Answer: d [Reason:] M20 grade of concrete is used in plain cement concrete sewer. It includes cement, fine aggregate and coarse aggregate in the ratio of 1:1.5:3.
3. Which of the following is incorrect regarding Cement concrete sewers?
a) They are economical
b) Can be manufactured at the site
c) They can be made of any desired strength
d) They cannot withstand tensile stress
Answer
Answer: d [Reason:] Cement concrete sewer can withstand internal and external pressure and are strong enough to resist both tensile and compressive stress.
4. The crown corrosion takes place due to formation of
a) CO2
b) H2O
c) H2S
d) HCl
Answer
Answer: c [Reason:] The crown corrosion takes place due to the formation of H2S which takes place because of aerobic and anaerobic condition in lower layers of sewage.
5. The cement concrete sewers are lined with vitrified clay lining to prevent
a) Dampness of sewer
b) Algae growth in the sewer
c) Crown corrosion
d) Foul smell of sewer
Answer
Answer: c [Reason:] The interiors of the sewers are lined with vitrified clay to prevent corrosion and erosion of sewer.
6. Which of the following method is not used for treating crown corrosion?
a) Full runs of sewer
b) Increasing the sulfate content of sewage
c) Aeration and chlorination of sewage
d) Vitrified clay lining of sewer
Answer
Answer: b [Reason:] The pretreatment of sewage is done for treating the crown corrosion to reduce the sulfate content from sewage.
7. Which of the following is incorrect regarding Stoneware sewer?
a) They can withstand tensile stress
b) They are highly resistant to sulfide corrosion
c) They have smooth interior
d) They are high compressive strength
Answer
Answer: a [Reason:] Stoneware sewer can not be used where sewage flow under pressure as they are weak in tension.
8. The range of diameter of cast iron sewer is
a) 20-100mm
b) 150-750mm
c) 40-250mm
d) 100-250mm
Answer
Answer: b [Reason:] The diameter of cast iron sewer lies between 150mm and 750mm and its length lies between 3 m to 3.5m.
9. Identify the correct statement from the following regarding Cast iron sewer.
a) They have low internal pressure
b) They are not leakage proof
c) They cannot withstand heavy external loads
d) They are preferred in water supply lines
Answer
Answer: d [Reason:] Cast iron is 100% leakage proof, so they are preferred in water supply lines.