civil engineering MCQs – Page 258

Practise multiple-choice questions from civil engineering for competitive examinations and subject revision. Review each marked answer and report any item that may be outdated or unclear.

civil engineering Mcqs
5141. Pick up the correct statement from the following?
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A. The circular section of sewers provides maximum hydraulic mean depth

B. The circular sewers work efficiently if the sections run at least half full

C. The circular sewers are provided for separate sewerage system

D. All the above
5142. Pick up the correct statement from the following?
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A. pH value indicates acidity and alkalinity of sewage

B. In acidic sewage, the pH value is less than 7

C. In alkaline sewage, the pH value is more than 7

D. All the above
5143. The amount of oxygen consumed by the aerobic bacterias which cause the aerobic biological decomposition of sewage, is known_________________?
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A. Chemical Oxygen Demand (C.O.D.)

B. Dissolved Oxygen (D.O.)

C. None of these

D. Bio-Chemical Oxygen Demand (B.O.D.)

5144. In sewers the effect of scouring is more on__________________?
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A. Horizontal side

B. Bottom side

C. All sides

D. Top side

5145. Pick up the correct statement from the following?
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A. Aerobic bacteria flourish in the presence of oxygen

B. Anaerobic bacteria flourish in the absence of oxygen

C. Facultative bacteria flourish with or without oxygen

D. . All the above
5146. Pick up the correct statement from the following ?
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A. All the above

B. The black colour indicates septic sewage

C. The sewage omits offensive odours after four hours

D. Turbidity is more in strong sewage

5147. Dilution method of disposing of sewage, is not preferred to_______________?
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A. When diluting water has high dissolved oxygen content

B. When diluting water is used for water supply near the point of sewage disposed

C. When the diluting water is having flow currents

D. When sewage is fresh

5148. The discharge per unit plan area of a sedimentation tank, is generally called________________?
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A. All the above

B. Over flow rate

C. Over flow velocity

D. Surface loading

5149. Pick up the incorrect statement from the following?
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A. The treated sewage effluents, are generally used for irrigating the crops

B. The mixture of water and waste products, is called sewage

C. The process of collecting, treating and disposing off the sewage, is called sewerage

D. The old convergence system was definitely better than water carried sewerage system
5150. The reduced levels of the string at the consecutive sight rails A and B are 203.575 m, 203.475 m respectively. If the difference of their R.D.s is 10 m, the gradient of the sewer line is_________________?
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A. 1 in 503 upward

B. 1 in 500 upward

C. 1 in 100 upward

D. 1 in 100 downward
5151. To prevent settling down of sewage both at the bottom and on the sides of a large sewer, self-cleaning velocity recommended for Indian conditions, is_________________?
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A. 0.50 m/sec

B. 0.75 m/sec

C. 0.70 m/sec

D. 0.60 m/sec

5152. The settling velocity of the particles larger than 0.06 mm in a settling tank of depth 2.4 is 0.33 m per sec. The detention period recommended for the tank, is____________________?
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A. 1 hour

B. 1 hour and 30 minutes

C. 2 hours

D. 30 minutes

5153. The gas which may cause explosion in sewers, is_________________?
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A. Methane

B. Ammonia

C. Carbondioxide

D. Carbon monoxide

5154. The sewage treatment units in which anaerobic decomposition of organic matter is used, are called________________?
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A. Imhoff tanks

B. Sludge sedimentation tanks

C. None of these

D. Trickling filters
5155. If the diameter of a sewer is 150 mm, the gradient required for generating self cleansing velocity, is________________?
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A. 1 in 100

B. 1 in 60

C. None of these

D. 1 in 120

5156. If q is the average sewage flow from a city of population P, the maximum sewage flow______________?
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A. Q = [(18 + P)/(4 + )] q

B. Q = [(18 + )/(4 + )] q

C. Q = [(5 + )/((15 + )] q

D. Q = [(4 + )/(18 + )] q

5157. Pick up the incorrect statement from the following?
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A. Sludge digestion is carried out in sludge tank

B. The gases produced in sludge digestion process, contain 75% carbon dioxide

C. The gases produced in sludge digestion process, contain 75% methane

D. The process of decomposing the organic matter under controlled anaerobic conditions, is called sludge digestion

5158. Pick up the correct statement from the following?
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A. Indore method of composting involves decomposition under aerobic conditions

B. Bangalore method of composting involves decomposing under anaerobic conditions

C. all of these

D. Fully stabilised refuse by the Bangalore method of compositing is a powdery mass called humus

5159. Pick up the incorrect statement from the following for allowing workers to enter sewers_______________?
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A. The men entering the manhole should be advised to smoke in the sewer

B. Proper tests for the presence of poisonous gases must be carried out

C. Warning signals should be erected

D. The particular manhole and one manhole on upstream and one manhole on downstream should remain open for 30 minutes

5160. The normal values of over flow rates for sedimentation tanks using coagulant, ranges between__________________?
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A. 40,000 to 50,000 litres/sqm/day

B. 80,000 to 100,000 litres/sqm/day

C. 50,000 to 60,000 litres/sqm/day

D. 25,000 to 35,000 litres/sqm/day