waste water engineering MCQs – Page 14

Practise focused waste water engineering questions with marked answers for exam preparation and subject revision.

waste water engineering Mcqs
261. A circular sewer section is preferred to because__________________?
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A. All the above

B. It is cheaper in construction

C. It provides maximum area for a given perimeter

D. It provides maximum hydraulic mean depth

262. Discrete or granular particles change their_________________ ?
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A. Weight

B. None of these

C. Size

D. Shape

263. A safety lamp when inserted in the upper portion of a manhole causes flames. It indicates the presence of______________?
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A. Methane gas

B. Carbondioxide gas

C. Petrol vapours

D. Hydrogen sulphide gas

264. In detritus tanks______________________?
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A. All the above

B. Organic and inorganic materials are separated

C. Detention period is kept 3 to 4 minutes

D. Flow velocity is kept 0.09 m/sec

265. The most widely used pump for lifting sewage is_________________?
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A. Pneumatic ejector

B. Reciprocating pump

C. Air pressure pump

D. Centrifugal pump
266. If the depletion of oxygen is found to be 5 ppm after incubating a 2.5% solution of sewage sample for 5 days at 21C, B.O.D. of the sewage is_____________________?
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A. 50 ppm

B. 150 ppm

C. 200 ppm

D. 100 ppm

267. Which one of the following gases is most significant as air pollutant ?
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A. Sulphur-dioxide

B. Carbondioxide

C. Oxygen

D. Nitrogen

268. If a 2% solution of sewage sample is incubated for 5 days at 20C and the dissolved oxygen depletion was found to be 8 mg/l. The BOD of the sewage is_________________?
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A. 300 mg/l

B. 400 mg/l

C. 200 mg/l

D. 100 mg/l

269. A well oxidized sewage contains nitrogen mainly as___________________?
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A. None of these

B. Free ammonia

C. Nitrites

D. Nitrates
270. Setting out the alignments of sewers may start from__________________?
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A. City

B. Tail end

C. Any point

D. Out-fall

271. The stone ware sewers_________________?
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A. Are used for carrying sewage and drainage from houses

B. All the above

C. After casting are dried and burnt at temperature 150C, 700C and 1200C

D. Are manufactured from clays and shale

272. The underground sewers are more subjected to________________?
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A. Bending force

B. Shearing force

C. Compressive force

D. Tensile force

273. The spacing of bars for perforations in coarse screens used for the treatment of sewage, is ____________________?
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A. 50 mm

B. 20 mm

C. 40 mm

D. 30 mm

274. Lead acetate test in sewer manhole is done to test the presence of ____________________?
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A. Diesel vapours

B. Hydrogen sulphide

C. Carbondioxide gas

D. Methane gas

275. The maximum depth of sedimentation tanks, is kept__________________?
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A. 3 m

B. 3.5 m

C. 4.5 m

D. 4 m

276. The ratio of the diameter of a circular section and the side of a square section hydraulically equivalent, is____________________?
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A. 1.085

B. 1.095

C. 1.075

D. 1.065

277. The factor responsible for purification of sewage in river is________________?
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A. Dissolved oxygen in water

B. All the above

C. Hydrology

D. Temperature

278. A five day B.O.D. at 15C of the sewage of a town is 100 kg/day. If the 5 day B.O.D. per head at 15C for standard sewage is 0.1 kg/day, the population equivalent is____________________?
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A. 1000

B. 10000

C. 100

D. 5000

279. Sewer pipes need be checked for_________________?
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A. Minimum flow

B. Maximum flow

C. Both A. and B.

D. None of these

280. The minimum diameter of a sewer is kept __________________?
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A. 25 cm

B. 15 cm

C. 10 cm

D. 20 cm