Practice Test: Question Set - 02
1. The gas which may cause explosion in sewers, is
- (A) Carbondioxide
- (B) Methane
- (C) Ammonia
- (D) Carbon
monoxide
2. Pick up the correct statement from the following:
- (A) The
water supply pipes carry pure water free from solid particles
- (B) The water
supply pipes get clogged if flow velocity is less than self cleansing velocity
- (C) The sewers
may be carried up and down the hills and valleys
- (D) The sewer
pipes are generally laid along level hills
3. Pick up the incorrect statement from the following:
- (A) The
process of decomposing the organic matter under controlled anaerobic
conditions, is called sludge digestion
- (B) Sludge
digestion is carried out in sludge tank
- (C) The gases
produced in sludge digestion process, contain 75% carbon dioxide
- (D) The gases
produced in sludge digestion process, contain 75% methane
4. The sewer pipes
- (A) Carry sewage
as gravity conduits
- (B) Are designed
for generating self-cleansing velocities at different discharge
- (C) Should
resist the wear and tear caused due to abrasion
- (D) All the
above
5. 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
- (A) 30 minutes
- (B) 1 hour
- (C) 1 hour and
30 minutes
- (D) 2 hours
6. The Chezy's constant C in the formula V = C √rs depends upon
- (A) Size of the
sewer
- (B) Shape of the
sewer
- (C) Roughness of
sewer surface
- (D) All the
above
7. The discharge per unit plan area of a sedimentation tank, is generally called
- (A) Over flow
rate
- (B) Surface
loading
- (C) Over flow
velocity
- (D) All
the above
8. Pick up the incorrect statement from the following for allowing workers to enter sewers
- (A) The
particular manhole and one manhole on upstream and one manhole on downstream
should remain open for 30 minutes
- (B) Proper tests
for the presence of poisonous gases must be carried out
- (C) The men
entering the manhole should be advised to smoke in the sewer
- (D) Warning
signals should be erected
9. For the open drain (N = 0.025) shown in the below figure, the discharge is
- (A) 26.88 cumecs
- (B) 27.88 cumecs
- (C) 28.88 cumecs
- (D) 29.88 cumecs
10. 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
- (A) 0.50 m/sec
- (B) 0.60 m/sec
- (C) 0.70 m/sec
- (D) 0.75 m/sec
11. Assertion (A): The determination of pH value of sewerage is important.
Reason (R):
The efficiency of certain treatment methods depends upon the availability of pH
value.
- (A) Both A and R
are true and R is the correct explanation of A
- (B) Both A and R
are true but R is not a correct explanation of A
- (C) A is true
but R is false
- (D) A is false
but R is true
12. The normal values of over flow rates for sedimentation tanks using coagulant, ranges between
- (A) 25,000 to
35,000 liters/sqm/day
- (B) 40,000 to
50,000 liters/sqm/day
- (C) 50,000 to
60,000 liters/sqm/day
- (D) 80,000 to
100,000 liters/sqm/day
13. The drainage area of a town is 12 hectares. Its 40% area is hard pavement (K = 0.85), the 40% area is unpaved streets (K = 0.20) and the remaining is wooded areas (K = 0.15). Assuming the time of concentration for the areas as 30 minutes and using the formula Ps = 900/(t + 60) the maximum run off is
- (A) 0.10 cumec
- (B) 0.12 cumec
- (C) 0.15 cumec
- (D) 0.20 cumec
14. Sewer pipes are designed for maximum discharge with 25% to 33% vacant cross-sectional area for
- (A) Unexpected
large scale infiltration of stream water
- (B) Unexpected
increase in the population
- (C) Under
estimates of maximum and average flows
- (D) All of the
above
15. The rational formula for peak drainage discharge, was evolved by
- (A) Fruhling
- (B) Lloyd David
- (C) Kuichling
- (D) All of these
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