# Environment Engineering MCQ ( Part-5 )

### WATER SUPPLY ENGINEERING

201 Most satisfactory formula for an estimate of fire demand Q for a city of population P in thousands for Indian conditions, is
(A) Q = 1115 (p/5 + 20)
(B) Q = 1640 âˆš???? (1 – 0.01 âˆš????)
(C) Q = 3180 âˆš????
(D) None of these
Ans. C

202 Permanent hardness of water can be removed by
(D) Zeolite process
Ans. D

203 The maximum depth of sedimentation tanks is limited to
(A) 2 m (B) (C) (D)
(B) 3 m
(C) 5 m
(D) 6 m
Ans. D

204 Pick up the incorrect statement from the following. Intake of water supply should
(A) Be nearer to the treatment plant
(B) Receive water from purer zone of the source
(C) Be located downstream of waste water disposal point
(D) Remain easily accessible during floods
Ans. C

205 The fire demand of a city may be worked out by
(A) Kuichling’s formula
(B) Freeman formula
(C) Under Writers formula
(D) All the above
Ans. D

206 The formula HL = nÂ²VÂ²L/R4/3 for the head loss in conduits is generally known as
(A) Hazen-William’s formula
(B) Manning’s formula
(C) Darcy-Weisbach formula
Ans. B

207 The joint used for joining the plain ends of cast iron pipes, is
(A) Flanged joint
(B) Socket and spigot joint
(C) Dresser coupling joint
(D) Flexible joint
Ans. C

208 Disinfection of water with ozone is not good because
(A) It vanishes before water reaches the consumers
(B) It removes the colour, taste and odour from water as bacterias
(C) It adds taste to the water
(D) It is more efficient than chlorine in killing bacterias
Ans. D

209 The prescribed hardness limit of potable water ranges between
(A) 50 to 75 P.P.M.
(B) 75 to 115 P.P.M.
(C) 100 to 150 P.P.M.
(D) 150 to 200 P.P.M.
Ans. B

210 While designing a water supply of an industrial township, industrial and commercial water demand of total supply, is assumed
(A) 10 % (B) (C) (D)
(B) 10 to 15 %
(C) 15 to 20 %
(D) 20 to 25 %
Ans. D

211 After cleaning a slow sand filter, the filtered water is not used for
(A) 6 hours to 12 hours
(B) 12 hours to 18 hours
(C) 18 hours to 24 hours
(D) 24 hours to 36 hours
Ans. D

212 The efficiency of sedimentation tank does not depend upon
(A) Depth of tank
(B) Length of tank
(C) Detention period
(D) Velocity of water
Ans. D

213 Velocity of flow of water in plain sedimentation water tank, is normally kept
(A) 3 cm/minute
(B) 10 cm/minute
(C) 20 cm/minute
(D) 30 cm/minute
Ans. D

214 The depth of the water table at a place is 45 m below the general ground level. To lift water from a deep tube well in such a locality, the type of pump to be installed is
(A) Centrifugal pump
(B) Reciprocating pump
(C) Deep well turbine pump
(D) None of these
Ans. C

215 In a well planned city, the layout of distribution pipes generally adopted, is
(A) Grid-iron system
(B) Interlaced system
(C) Reticulation system
(D) All the above
Ans. D

216 Pick up the incorrect statement from the following:
(A) Free surface ground water is subjected to atmospheric pressure
(B) Water table surface rises and falls with seasons
(C) Depth of water table is directly proportional to the rate of drawl of water
(D) Level of water table remains stationary
Ans. D

217 Pick up the incorrect statement from the following:
(A) The flow in strainer type wells is radial (B) (C) (D)
(B) The flow in cavity type wells in spherical
(C) In strainer type wells, area of flow depends upon the length of the strainer pipe
(D) In cavity type wells, area of flow depends upon the size of the cavity
Ans. C

218 As per IS : 1172-1963, water required per head per day for average domestic purposes, is
(A) 50 litres
(B) 65 litres
(C) 85 litres
(D) 135 litres
Ans. D

219 The duration of contact of chlorine with water before it is served to the first consumer, should be at least
(A) 10 to 15 minutes
(B) 15 to 20 minutes
(C) 20 to 30 minutes
(D) 30 to 40 minutes
Ans. C

220 Water supply system includes
(A) Digging a well for water
(B) Construction of dams
(C) Construction of canals
(D) Entire arrangement from source to distribution
Ans. D

221 The maximum pressure to which a pipe is subjected to during its operation, is known
(A) Working pressure
(B) Design pressure
(C) Test pressure
(D) Pipe pressure
Ans. A

222 For the same draw down in two observations wells at distances r1 and r2, the times after start of pumping are t1 and t2 hours respectively. The relation which holds good is
(A) t2 = r2/r1 Ã— t1
(B) t2 = (r2/r1)Â² Ã— t1
(C) t2 = (r2/r1)3 Ã— t1
(D) t2 = (r2/r1) Ã— t12
Ans. B

223 A slow sand filter is cleaned if its filter head is higher than
(A) 10 cm to 20 cm
(B) 20 cm to 40 cm
(C) 40 cm to 70 cm
(D) 70 cm to 120 cm
Ans. D

224 The intake opening is generally covered by a screen to prevent entry of debris etc. and its level is kept
(A) At the level of water of the source
(B) At the bottom of water of the source
(C) At about 2.5 m above the bottom
(D) None of these
Ans. C

225 If four fires break out in a city of population 40 lakhs and if each hydrant has three streams and duration of each fire is four hours, the total quantity of water required, is
(A) 1880 kilo litres
(B) 2880 kilo litres
(C) 3880 kilo litres
(D) 4880 kilo litres
Ans. B

226 Steel pipe are
(A) Suitable for withstanding high internal pressure
(B) Connected by riveted or welded joints
(C) Generally laid underground and no expansion joint is required
(D) Likely to last 100 years under ordinary conditions
Ans. D

227 When gravity and pumping systems of water distribution are adopted, the type of distribution reservoir, is
(A) Elevated tank
(B) Ground source reservoir
(C) Intz tank
(D) Stand pipe
Ans. A

228 The force which develops in a pressure conduit supported on trestles, is
(A) Tension
(B) Compression
(C) Temperature stress
(D) Flexural stress
Ans. D

229 Standard unit of turbidity of water is in one litre of distilled water, one milligram of finely divided
(A) Silica
(B) Mud
(C) Clay
(D) Organic matter
Ans. A

230 For complete stabilisation of organic matter in polluted water, it takes
(A) 5 days
(B) 10 days
(C) 20 days
(D) 30 days
Ans. D

231 If intensity of rainfall in cm per hour is I, percentage coefficient of run-off is P, area of catchment in square kilometres is A, the total run-off Q, is given by
(A) Q = 1.758 Ã— 102 Ã— API (B) (C) (D)
(B) Q = 2.758 Ã— 102 Ã— API
(C) Q = 2.758 Ã— 103 Ã— API
(D) Q = 2.758 Ã— 103 Ã— A/PI
Ans. C

232 Shales are
(A) Porous
(B) Permeable
(C) Porous and permeable
(D) Porous but not permeable
Ans. D

233 The best process of disinfection of public water supply, is by
(A) Boiling
(B) Chlorination
Ans. B

234 The dilution ratio at which the odour is hardly detectable is generally called threshold odour number and for public supplies it should not exceed
(A) 3
(B) 5
(C) 7
(D) 9
Ans. A

235 Surge tanks are used
(A) For storage water
(B) To increase the velocity in a pipeline
(C) As overflow valves
(D) To guard against water hammer
Ans. D

236 Normal values of overflow rate for plain sedimentation tanks in litres/hr/m2 , generally range between
(A) 100 to 250
(B) 250 to 500
(C) 500 to 750
(D) 750 to 1000
Ans. C

237 P.V.C. pipes can withstand pressure bead of water upto
(A) 25 m
(B) 50 m
(C) 75 m
(D) 100 m
Ans. D

238 Most commonly used pump for lifting water in water supply mains, is
(A) Axial flow pump
(B) Reciprocating pump
(C) Rotary type pump
(D) Centrifugal pumps
Ans. A

239 The fire demand for a city of 50,000 populations, according to Godrich formula, is
(A) 40 mld
(B) 42 mld
(C) 44 mld
(D) 48 mld
Ans. C

240 If V is total consumption of water in litres for a population of N individuals, per capita consumption or water allowance for the water supply Q, is given by
(A) Q = V/12N
(B) Q = V/24N
(C) Q = V/265N
(D) None of these
Ans. C

241 For controlling algae, the most commonly used chemical, is
(A) Copper sulphate
(B) Alum
(C) Lime
(D) Bleaching powder
Ans. A

242 The storage capacity of a reservoir may be divided into three zones. The lowest zone is
(B) Useful storage
(C) Surcharge storage
(D) None of these
Ans. A

243 Economic height of a dam is the height corresponding to which
(A) Cost of the dam per unit of storage is minimum
(B) Amount of silting is less
(C) Cost of dam per unit storage is maximum
(D) Free board provided is least
Ans. A

244 For maximum alkalinity of water, pH value should be
(A) Zero
(B) Less than 7
(C) More than 7
(D) 14
Ans. D

245 The efficiency of a pumping set, is generally assumed
(A) 50 %
(B) 55 %
(C) 60 %
(D) 65 %
Ans. D

246 The population growth curve is
(A) S-shaped curve
(B) Parabolic curve
(C) Circular curve
(D) Straight line
Ans. A

247 The fire demand for ascertaining the empirical formula 1136.5 [(P/10) + 10] known as
(A) Kuichling’s formula
(B) Buston’s formula
(C) Freeman formula
(D) Under Writers formula
Ans. C

248 The bacterias which may survive with or without free oxygen, are called
(A) Aerobic bacterias
(B) Anaerobic bacterias
(C) Facultative bacteria’s
(D) None of these
Ans. C

249 Aeration of water is done to remove
(A) Odour
(B) Colour
(C) Bacterias
(D) Turbidity
Ans. A

250 The maximum pressure to which cast iron pipes may be subjected to, is
(A) 3 kg/cm2
(B) 5 kg/cm2
(C) 7 kg/cm2
(D) 10 kg/cm2
Ans. C