Practice Test: Question Set - 08
1. The type of valve which is provided to control the flow of water in the distribution system at street corners and where the pipe lines intersect is
- (A) Check valve
- (B) Sluice valve
- (C) Safety valve
- (D) Scour valve
2. The design discharge for the separate sewer system shall be taken as
- (A) Equal to dry weather flow (DWF)
- (B) 2 × DWF
- (C) 3 × DWF
- (D) 6 × DWF
3. The most commonly used sewer under culverts is
- (A) Circular brick sewer
- (B) Circular cast iron sewer
- (C) Semi-elliptical sewer
- (D) Horseshoe type sewer
4. The relative stability of a sewage sample, whose dissolved oxygen is same as the total oxygen required to satisfy BOD, is
- (A) 1
- (B) 100
- (C) Infinite
- (D) Zero
5. For satisfactory working of a sludge digestion unit, the pH range of digested sludge should be maintained as
- (A) 4.5 to 6.0
- (B) 6.5 to 8.0
- (C) 8.5 to 10.0
- (D) 10.5 to 12.0
6. As compared to geometrical increase method of forecasting population, arithmetical increase method gives
- (A) Lesser value
- (B) Higher value
- (C) Same value
- (D) Accurate value
7. The phenolic compounds in public water supply should not be more than
- (A) 0.1 ppm
- (B) 0.01 ppm
- (C) 0.001 ppm
- (D) 0.0001 ppm
8. Percentage of bacterial load that can be removed from water by the process of plain sedimentation is about
- (A) 10 to 25
- (B) 50
- (C) 75
- (D) 100
9. Double filtration is used
- (A) To increase the filtration slow sand filters
capacity of
- (B) To increase the filtration rapid sand
filters capacity of
- (C) For isolated buildings like pools, hotels
etc swimming
- (D) All of the above
10. The major disadvantage of lime soda process of water softening is that
- (A) It is unsuitable for turbid and acidic water
- (B) Huge amount of precipitate is formed which creates
a disposal problem
- (C) The effluent cannot be reduced to zero
hardness
- (D) It is unsuitable for softening the water of
excessive hardness
11. Scour valves are provided
- (A) At street corners to control the flow of
water
- (B) At every depression and dead ends to drain out the
waste water that may collect there
- (C) At the foot of rising main along the slope to
prevent back running of water
- (D) At every summit of rising mains
12. The velocity of flow does not depend on
- (A) Grade of sewer
- (B) Length of sewer
- (C) Hydraulic mean depth of sewer
- (D) Roughness of sewer
13. The ratio of 5 day BOD to ultimate BOD is about
- (A) 1/3
- (B) 2/3
- (C) 3/4
- (D) 1.0
14. Septic tank is a
(i) Settling tank
(ii) Digestion tank
(iii) Aeration tank
The correct answer is
- (A) Only (i)
- (B) (i) and (ii)
- (C) (i) and (iii)
- (D) Only (iii)
15. The population of a town in three consecutive years are 5000, 7000 and 8400 respectively. The population of the town in the fourth consecutive year according to geometrical increase method is
- (A) 9500
- (B) 9800
- (C) 10100
- (D) 10920
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