Practice Test: Question Set - 17
1. The settlement velocity of a solid (diameter 0.5 mm, specific gravity 1.75) in water having temperature 10°C, is
- (A) 213.5 cm/sec
- (B) 313.5 cm/sec
- (C) 413.5 cm/sec
- (D) 500 cm/sec
2. For house drainage minimum gradient is
- (A) 1 in 60
- (B) 1 in 80
- (C) 1 in 10
- (D) 1 in 400
3. For estimating the peak run off the rational formula Q = 0.0278 KpA was evolved by
- (A) Kinchling
- (B) Lloyd
Davis
- (C) Frubling
- (D) All the
above
4. A rain sanitary sewer is constructed to carry
- (A) Sanitary
sewage
- (B) Storm
sewage
- (C) Surface
water
- (D) Ground water
5. The most effective arrangement for diverting excess storm water into a natural drainage, is
- (A) Leaping weir
- (B) Overflow
weir
- (C) Siphon spill
way
- (D) None of
these
6. The drop man holes are generally provided in sewers for
- (A) Industrial
areas
- (B) Large town
ships
- (C) Hilly town
ships
- (D) Cities in plains
7. For a peak discharge of 0.0157 cumec, with a velocity of 0.9 m/sec, the diameter of the sewer main, is
- (A) 10 cm
- (B) 12 cm
- (C) 15 cm
- (D) 18 cm
8. For design purposes, the normal rate of infiltration of ground water into the sewer, is
- (A) 500
liters/km/cm
- (B) 1000
liters/km/cm
- (C) 1500
liters/km/cm
- (D) 2000
liters/km/cm
9. You are asked to design sewer pipes of diameters 0.4 m to 0.9 m at maximum flow, you will assume the sewer flow running at
- (A) Full depth
- (B) Half full
- (C) Two third
full
- (D) Three fourth
full
10. The algae dies out in the zone of
- (A) Degradation
- (B) Active
decomposition
- (C) Recovery
- (D) Cleaner
water
11. In a sludge digestion tank if the moisture content of sludge V1 litres is reduced from p1 % to p2 % the volume V2 is
- (A) [(100 + P1)/(100 - P2)] V1
- (B) [(100 - P1)/(100 + P2)] V1
- (C) [(100 - P1)/(100 - P2)] V1
- (D) [(100 + P2)/(100 - P1)] V1
12. Assertion (A) : Discharging the effluents from the oxidation ponds just up stream of lakes or reservoirs is undesirable.
Reason (R) :
The discharged algae get settled in the reservoirs and cause anaerobic decomposition
and other water qualities.
- (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
13. The sewage treatment in septic tanks is due to
- (A) Anaerobic
decomposition
- (B) Aerobic
decomposition
- (C) Parasitic
decomposition
- (D) None of
these
14. The dimensions of a rectangular settling tank are: length 24 m, width 6 m and depth 3 m. If 2 hour detention period for tanks is recommended, the rate of flow of sewage per hour, is
- (A) 204 cu.m
- (B) 208 cu.m
- (C) 212 cu.m
- (D) 216 cu.m
15. If ‘n’ is the rugosity coefficient, ‘r’ is the hydraulic depth, ‘s’ is the bed slope of sewer, the velocity of flow in m/sec may be obtained by the formula V = (1/n) r2/3 s1/2 evolved by
- (A) Chezy
- (B) Manning
- (C) Bazin
- (D) Kutter
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