Practice Test: Question Set - 13
1. The flow velocity in detritus tanks is
- (A) 0.05 m/sec
- (B) 0.09 m/sec
- (C) 1.25 m/sec
- (D) None of
these
2. If the side of a square sewer is 1000 mm, the diameter of a hydraulically equivalent circular section, is
- (A) 1045 mm
- (B) 1065 mm
- (C) 1075 mm
- (D) 1095 mm
3. The water carried sewerage system removes
- (A) Domestic
sewage
- (B) Industrial
sewage
- (C) Storm
sewage
- (D) All
the above
4. A nuisance is experienced in diluting water if dilution factor is less than
- (A) 100
- (B) 60
- (C) 40
- (D) 20
5. A manhole is generally provided at each
- (A) Bend
- (B) Junction
- (C) Change
of gradient
- (D) All the
above
6. The asbestos cement pipes are generally laid
- (A) Horizontally
- (B) Vertically
- (C) At an angle
of 30°
- (D) At an angle
of 60°
7. The design period in years for pumping plants, is
- (A) 1
- (B) 2 to 3
- (C) 3 to 5
- (D) 5 to 10
8. A safety lamp when inserted in the upper portion of a manhole causes flames. It indicates the presence of
- (A) Carbondioxide
gas
- (B) Hydrogen
sulphide gas
- (C) Methane gas
- (D) Petrol
vapors
9. The disintegrating pump in which solid matter is broken up before passing out, is
- (A) Centrifugal
pump
- (B) Reciprocating
pump
- (C) Pneumatic
ejector
- (D) None
of these
10. If the depletion of oxygen is found to be 2.5 mg/liter after incubating 2.5 ml of sewage diluted to 250 ml for 5 days at 20°C, B.O.D. of the sewage is
- (A) 50 mg/l
- (B) 100 mg/l
- (C) 150 mg/l
- (D) 250 mg/l
11. Design period of 40 to 50 years is adopted for
- (A) Branch
sewers
- (B) Main
sewers
- (C) Trunk
sewers
- (D) All the
above
12. A circular sewer section is preferred to because
- (A) It is
cheaper in construction
- (B) It provides
maximum area for a given perimeter
- (C) It provides
maximum hydraulic mean depth
- (D) All the
above
13. In very first stage of decomposition of the organic matter in sewage
- (A) Nitrites are
formed
- (B) Nitrates
are formed
- (C) Carbondioxide
is formed
- (D) Ammonia is
formed
14. In a city the ratio of the drainage to sewage is 20, the percentage discharge passing through non-monsoon periods, is
- (A) 5
- (B) 10
- (C) 15
- (D) 20
15. The self-cleansing velocity of water flowing through pipe lines, is
- (A) 2 meters/sec
- (B) 1 metre/sec
- (C) 0.5
metre/sec
- (D) 0.25
metre/sec
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