Environment Engineering MCQ
WATER SUPPLY ENGINEERING
148 When the reduced level of the water source is higher than the reduced level of the consumer’s place, water is generally supplied
(A) By pumping system
(B) By gravitational system
(C) Both (a) and (b)
(D) All the above
Ans. B
149 Surcharge storage zone of a reservoir, is
(A) Below dead storage (B) (C) (D)
(B) Between dead storage and useful storage
(C) Above useful storage
(D) Also known as valley storage
Ans. C
150 In pressure supply mains, water hammer pressure is reduced by providing
(A) Sluice valves
(B) Air valves
(C) Pressure relief valves
(D) None of these
Ans. C
151 Specific capacity or yield of wells, is generally expressed, as
(A) m 3 per sec
(B) m 3 /hour
(C) m 3 /hour/m2
(D) m 3 /hour/m2 /m
Ans. D
152 Turbidity of raw water is a measure of
(A) Suspended solids
(B) Acidity of water
(C) B.O.D.
(D) None of these
Ans. A
153 If the chosen diameter of a pipe, is less than the economical diameter
(A) Cost of pipe will be less
(B) Head loss will be high
(C) Cost of pumping will be more than saving
(D) All the above
Ans. D
154 While determining the yield of open wells by the pumping test
(A) Velocity of recharging water, increases with depression head
(B) Depression head resulting at critical velocity, is called critical depression head
(C) Working head is generally limited to 1/3 rd of the critical depression head
(D) Maximum safe yield of an open well, is expected at critical depression head
Ans. D
155 The process of passing water through beds of granular materials, is called
(A) Screening
(B) Sedimentation
(C) Filtration
(D) None of these
Ans. C
156 For the prediction of future population of a city, the factor to be considered, is
(A) Births
(B) Deaths
(C) Migrants
(D) All the above
Ans. D
157 Mathamoglobinemia or blue baby disease is caused due to
(A) Chlorides
(B) Nitrites
(C) Nitrates
(D) Sulphides
Ans. C
158 To control the growth of algae in reservoirs, the compound which is used, is
(A) Bleaching powder
(B) Copper sulphate
(C) Lime solution
(D) Alum solution
Ans. B
159 A pressure conduit laid underground, may not be subjected to
(A) Internal pressure of water
(B) Pressure due to external load
(C) Longitudinal temperature stress
(D) Longitudinal stresses due to unbalanced pressure to bends
Ans. C
160 The bacterias which require free oxygen for their survival, are called
(A) Aerobic bacterias
(B) Anaerobic bacterias
(C) Facultative bacteria
(D) None of these
Ans. A
161 Gravity conduits are generally in the form of
(A) Canals
(B) Flumes
(C) Aqueduct
(D) All the above
Ans. D
162 The bed slope in slow sand filters, is generally kept
(A) 1 in 50
(B) 1 in 75
(C) 1 in 100
(D) 1 : 200
Ans. C
163 Perched aquifers are generally found
(A) On the surface of the ground
(B) Below the surface of the ground but above water table
(C) Below the water table
(D) All the above
Ans. B
164 Pick up the incorrect statement from the following:
(A) The pH value of water indicates the logarithm of reciprocal of hydrogen ion concentration in water
(B) Higher value of pH means lower hydrogen ion concentration
(C) Lower value of pH means higher hydrogen ion contraction
(D) Lower value of pH gives alkaline solution
Ans. D
165 Mostly used coagulant, is
(A) Chlorine
(B) Alum
(C) Lime
(D) Bleaching powder
Ans. B
166 A centrifugal pump is required to be primed before starting if it is located
(A) At higher level than water level of reservoir
(B) At lower level than water level of reservoir
(C) Both (a) and (b)
(D) Neither (a) nor (b)
Ans. A
167 Normal values of overflow rate for plain sedimentation tank, is
(A) 250 to 500 litres/hr/m2
(B) 500 to 750 litres/hr/m2
(C) 750 to 1000 litres/hr/m2
(D) 1000 to 1250 litres/hr/m2
Ans. B
168 ‘Shrouding’ is essentially provided in
(A) Strainer type wells
(B) Cavity type wells
(C) Slotted type well
(D) All the above
Ans. C
169 The maximum permissible hardness for public supplies is
(A) 95 mg/litre
(B) 105 mg/litre
(C) 115 mg/litre
(D) 125 mg/litre
Ans. C
170 The chlorine supply cylinders are generally kept at 38°C to 40°C to prevent
(A) Conversion into crystals
(B) It from burning
(C) It from explosion
(D) None of these
Ans. A
171 For calculation of economical diameter D of a pipe in metres for a discharge Q to be pumped in cumecs, Lea suggested the empirical formula
(A) D = 0.22 √????
(B) D = 1.22√????
(C) D = 2.22√????
(D) D = 3.22 √????
Ans. B
172 An earth formation which, although porous and capable of absorbing water does not provide an appreciable supply to wells, is known as
(A) Aquifer
(B) Aquiclude
(C) Aquifuge
(D) None of these
Ans. B
173 Property of earth to allow water to pass through it, is known as
(A) Perviousness
(B) Porosity
(C) Permeability
(D) Transmissibility
Ans. A
174 If G is the specific gravity of particles of diameter d, the velocity of settlement V in still water at T°C, according to Stoke’s law, is
(A) V = 418 (G – 1) d² [(3T + 70)/100]
(B) V = 418 (G – 1) d [(3T – 70)/100]
(C) V = 418 (G – 1) d² [(2T + 70)/100]
(D) V = 418 (G – 1) d 4 [(3T + 70)/100]
Ans. A
175 Distribution mains of any water supply, is normally designed for its average daily requirement
(A) 100 %
(B) 150 %
(C) 200 %
(D) 225 %
Ans. D
176 Maximum threshold number permitted for indicating the odour of public water supplies, is
(A) 1
(B) 2
(C) 3
(D) 4
Ans. C
177 The rate of silting in a reservoir
(A) Is less in the beginning
(B) Remains constant throughout
(C) Is more in the beginning
(D) is more in the beginning and reduces in the end
Ans. D
178 Corrosion of well pipes may not be reduced by
(A) Reducing the draw down and the pumping rate
(B) Reducing the flow velocity
(C) Using thicker pipes
(D) Using screens having larger area of openings
Ans. D
179 Recuperation test is carried out to determine
(A) Turbidity of water
(B) pH value of water
(C) Yield of well
(D) Discharge from a well
Ans. A
180 Pick up the incorrect statement from the following. The underground sources of water, is from
(A) Wells
(B) Springs
(C) Infiltration wells
(D) Storage reservoirs
Ans. D
181 Most important method for calculating discharge for planning a water supply project, is
(A) Velocity area method
(B) Weir or spillway method
(C) Use of venturi-meter
(D) Using power plant consumption
Ans. A
182 In a rapid sand filter, air binding is caused due to excessive
(A) Negative pressure
(B) Pressure
(C) Turbidity
(D) Water pressure
Ans. A
183 One degree of hardness of water means a content of salts of
(A) 10.25 mg/litre
(B) 12.25 mg/litre
(C) 14.25 mg/litre
(D) 16.25 mg/litre
Ans. C
184 The U.C. (uniformity coefficient) D60/D10 for the best filter media sand should be
(A) 2
(B) 3
(C) 4
(D) 5
Ans. A
185 Manholes are less common in
(A) Cast iron pipes
(B) Steel pipes
(C) Hume steel pipes
(D) R.C.C. pipes
Ans. A
186 For determining the velocity of flow of underground water, the most commonly used nonempirical formula is
(A) Darcy’s formula
(B) Slichter’s formula
(C) Hazen’s formula
(D) Lacy’s formula
Ans. A
187 The most commonly used chemical for de-chlorination of water, is
(A) Sodium thiosulphate
(B) Sodium bisulphate
(C) Sodium sulphite
(D) Sulphur-dioxide
Ans. C
188 To remove very fine suspended particles from water, the method adopted is
(A) Screening
(B) Sedimentation
(C) Boiling
(D) Filtration
Ans. D
189 Sunlight
(A) Helps growth of bacterias
(B) Impedes growth of algae
(C) Increases dissolved oxygen content
(D) Reduces turbidity
Ans. B
190 The detention period for plain sedimentation water tanks, is usually
(A) 4 to 8 hours
(B) 8 to 16 hours
(C) 16 to 24 hours
(D) 24 to 36 hours
Ans. D
191 Air valves are generally provided in pressure pipes of water supply
(A) At pipe junctions (B) (C) (D)
(B) At summits
(C) At low points
(D) Near service pipes
Ans. B
192 The gaseous form of chlorine gets converted into liquid form when subjected to a pressure of
(A) 5 kg/cm2
(B) 6 kg/cm2
(C) 7 kg/cm2
(D) 10 kg/cm2
Ans. C
193 Flow through period, in sedimentation tanks, is
(A) Equal to detention period
(B) More than detention period
(C) Less than detention period
(D) Detention period divided by displacement efficiency
Ans. C
194 The maximum hourly consumption, is generally taken as
(A) 110 %
(B) 120 %
(C) 140 %
(D) 150 %
Ans. D
195 Hardness of water can be removed by boiling if it is due to
(A) Calcium bicarbonates
(B) Calcium sulphates
(C) Calcium chloride
(D) Calcium nitrates
Ans. A
196 Hardness of water is caused by
(A) Presence of soap lather
(B) Presence of chlorides and sulphates of sodium and potassium
(C) Presence of bicarbonates, sulphates or chlorides of calcium and magnesium
(D) Turbidity
Ans. C
197 The average domestic consumption under normal conditions in an Indian city per day per person, is
(A) 105 litres
(B) 115 litres
(C) 125 litres
(D) 135 litres
Ans. D
198 If d is the diameter of the pipe, p is the total internal pressure, f is the permissible tensile stress and n is the effective of the joint, the thickness t of metal pipe, is
(A) n (pd/2f)
(B) (1/n) (pd/2f)
(C) (1/n) (pd/3f)
(D) (1/n) (pf/d)
Ans. B
199 Generally, first portion of a logistic curve for the population growth of a developing city, represents the growth of
(A) Increasing
(B) Decreasing
(C) Constant
(D) All the above
Ans. A
200 A pressure conduit carrying water beneath a stream or a canal, is known as
(A) Sag (B) (C) (D)
(B) Depressed pipe
(C) Inverted syphon
(D) All the above
Ans. D
