Environment Engineering MCQÂ
101 Anti syphonage pipe is fitted
(A) At the end of septic tanks (B) (C) (D)
(B) On manholes
(C) With a W.C. trap
(D) At the beginning of sewer line
Ans. C
102 In a grit chamber of a sewage treatment plant,
(A) Flow velocity 0.15 m to 0.3 m/sec is kept
(B) Depth of 0.9 m to 1.20 m is kept
(C) One minute of detention period is kept
(D) All the above
Ans. D
103 The ratio of maximum sewage flow to average sewage flow for mains up to 1 m in diameter, is
(A) 1.5 (B) (C) (D)
(B) 2.0
(C) 3.0
(D) 4.0
Ans. B
104 pH value of sludge during alkaline regression stage, is
(A) More than 7
(B) Less than 7
(C) Less than 6
(D) More than 6
Ans. A
105 The arrangement made for passing the sewer line below an obstruction below the hydraulic gradient lines called
(A) Inverted syphon
(B) Depressed sewer
(C) Sag pipe
(D) all of these
Ans. D
106 Pick up the incorrect size of stone ware sewers
(A) 52.5 cm
(B) 67.5 cm
(C) 82.5 cm
(D) None of these
Ans. D
107 Chlorination of water is done for the removal of
(A) Bacterias
(B) Suspended solids
(C) Sediments
(D) Hardness
Ans. A
108 Sludge banks are formed if sewage is disposed of in
(A) Rivers
(B) Seas
(C) Lakes
(D) None of these
Ans. B
109 The clarigesters are
(A) Circular septic tanks
(B) Rectangular septic tanks
(C) Circular Imhoff double tanks with bottom hoppers
(D) Circular Imhoff double storey tanks without bottom hoppers
Ans. D
110 The spacing of bars for perforations in coarse screens used for the treatment of sewage, is
(A) 20 mm
(B) 30 mm
(C) 40 mm
(D) 50 mm
Ans. D
111 The pH value of fresh sewage is usually
(A) Equal to 7
(B) More than 7
(C) Less than 7
(D) Equal to zero
Ans. B
112 The maximum depth of sedimentation tanks, is kept
(A) 3 m
(B) 3.5 m
(C) 4 m
(D) 4.5 m
Ans. A
113 Lead caulked joints are used for laying
(A) Stone ware pipes
(B) Earthenware pipes
(C) C.I. pipes
(D) G.I. pipes
Ans. B
114 If D is the diameter of a circular sewer and D’ is the top horizontal diameter of an equivalent egg shaped section, the relationship which holds good, is
(A) D’ = 0.64 D
(B) D’ = 0.74 D
(C) D’ = 0.84 D
(D) D’ = 0.94 D
Ans. C
115 The spacing of man holes along a straight portion of a sewer is 300 m, the diameter of the sewer may be
(A) 0.9 cm
(B) 1.2 m
(C) 1.5 m
(D) > 1.5 m
Ans. D
116 The quantity of liquid waste which flows in sewers during the period of rainfall, is known
(A) Sanitary sewage
(B) Industrial waste
(C) Storm sewage
(D) None of these
Ans. C
117 Nitrogen cycle of sewage, is
(A) Liberation of ammonia-formation of nitrites-formation of nitrates-liberation of nitrogen
(B) Liberation of nitrogen-liberation of ammonia-formation of nitrites- formation of nitrates
(C) Liberation of nitrogen-formation of nitrates-formation of nitrites-liberation of ammonia
(D) Formation of nitrates-formation of nitrites-liberation of nitrates-liberation of nitrates
Ans. A
118 Depletion of ozone layer in the outer atmosphere may cause
(A) Lung cancer
(B) Skin cancer
(C) Bronchitis
(D) Heart disorder
Ans. B
119 The minimum diameter of a sewer is kept
(A) 10 cm
(B) 15 cm
(C) 20 cm
(D) 25 cm
Ans. B
120 Which one of the following gases is most significant as air pollutant?
(A) Carbondioxide (B) (C) (D)
(B) Oxygen
(C) Nitrogen
(D) Sulphur-dioxide
Ans. D
121 Hazen’s formula VS = 418 (GS – Gw)d [(3T + 70)/100] is used for the settlement velocity of the particles of diameter
(A) Less than 0.01 mm
(B) Less than 0.05 mm
(C) Less than 0.1 mm
(D) Greater than 0.1 mm
Ans. D
122 For sewers, inverted siphon is provided for
(A) One pipe
(B) Two pipes
(C) Three pipes
(D) Four pipes
Ans. C
123 For large sewers, maximum distance between manholes may be
(A) 50 m
(B) 100 m
(C) 200 m
(D) 300 m
Ans. D
124 In sewers designed with self cleansing velocity,
(A) The bottom is silted
(B) The bottom is scoured
(C) Both silting and scouring occur at the bottom
(D) Neither silting nor scouring occurs at the bottom
Ans. D
125 The value of Chezy’s constant C = 157.6/(1.81 + K/√???? ) is used in
(A) Chezy’s formula
(B) Bazin’s formula
(C) Kutter’s formula
(D) Manning’s formula
Ans. B
126 Pathogens (or pathogenic bacteria’s) in water may cause
(A) Typhoid
(B) Cholera
(C) Dysentery
(D) All the above
Ans. D
127 The rate of accumulation of sludge per person per year, is
(A) 10 litres (B) (C) (D)
(B) 15 litres
(C) 20 litres
(D) 25 litres
Ans. C
128 The screens are fixed
(A) Perpendicular to the direction of flow
Faculty of Degree Engineering – 083
Department of Civil Engineering – 06
(B) Parallel to the direction of flow
(C) At an angle 30° to 60° to the direction of flow
(D) None of these
Ans. C
129 In circular sewers if depth of flow is 0.2 times the full depth, the nominal gradient,
(A) Is only provided
(B) Is doubled
(C) Is trebled
(D) Is not enough
Ans. B
130 In detritus tanks
(A) Flow velocity is kept 0.09 m/
(B) Detention period is kept 3 to 4 minutes
(C) Organic and inorganic materials are separated
(D) All the above
Ans. D
131 The flow velocity in detritus tanks is
(A) 0.05 m/sec
(B) 0.09 m/sec
(C) 1.25 m/sec
(D) None of these
Ans. B
132 If the side of a square sewer is 1000 mm, the diameter of a hydraulically equivalent circular section, is
(A) 1045 mm
(B) 1065 mm
(C) 1075 mm
(D) 1095 mm
Ans. D
133 A nuisance is experienced in diluting water if dilution factor is less than
(A) 100
(B) 60
(C) 40
(D) 20
Ans. D
134 A manhole is generally provided at each
(A) Bend
(B) Junction
(C) Change of gradient
(D) All the above
Ans. D
135 The asbestos cement pipes are generally laid
(A) Horizontally
(B) Vertically
(C) At an angle of 30°
(D) At an angle of 60°
Ans. B
136 The design period in years for pumping plants, is
(A) ) 1
(B) 2 to 3
(C) 3 to 5
(D) 5 to 10
Ans. D
137 A safety lamp when inserted in the upper portion of a manhole causes flames. It indicates the presence of
(A) Carbondioxide gas
(B) Hydrogen sulphide gas
(C) Methane gas
(D) Petrol vapours
Ans. C
138 Design period of 40 to 50 years is adopted for
(A) Branch sewers
(B) Main sewers
(C) Trunk sewers
(D) All the above
Ans. D
139 In very first stage of decomposition of the organic matter in sewage
(A) Nitrites are formed
(B) Nitrates are formed
(C) Carbondioxide is formed
(D) Ammonia is formed
Ans. D
140 In a city the ratio of the drainage to sewage is 20, the percentage discharge passing through nonmonsoon periods, is
(A) 5
(B) 10
(C) 15
(D) 20
Ans. D
141 The self-cleansing velocity of water flowing through pipe lines, is
(A) 2 metres/sec
(B) 1 metre/sec
(C) 0.5 metre/sec
(D) 0.25 metre/sec
Ans. A
142 In case of sewer lines
(A) Water test is carried out to check water tightness of the joints
(B) Test for straightness is carried out with the help of a lamp and mirror
(C) Obstruction test is carried out with the help of smooth ball of diameter 13 mm
(D) All the above
Ans. D
143 The normal values of over flow rates for secondary sedimentation tanks, ranges between
(A) 25,000 to 35,000 litres/sqm/day
(B) 40,000 to 50,000 litres/sqm/day
(C) 50,000 to 60,000 litres/sqm/day
(D) 80,000 to 10,000 litres/sqm/day
Ans. A
144 A manhole is classified as shallow if its depth is between
(A) 0.4 to 0.5 m
(B) 0.5 to 0.7 m
(C) 0.7 to 0.9 m
(D) 0.9 to 1.20 m
Ans. C
145 The first stage of neutral process of sludge digestion, is
(A) Acid fermentation
(B) Acid regression
(C) Alkaline fermentation
(D) None of these
Ans. A
146 The formula V = (1/n) r2/3√???? used for determining flow velocities in sewers is known as,
(A) Chezy’s formula
(B) Bazin’s formula
(C) Kutter’s formula
(D) Manning’s formula
Ans. D
147 In sewers the highest non-scouring velocity is achieved in
(A) Glazed bricks sewers
(B) Cast iron sewers
(C) Cement concrete sewers
(D) Stone ware sewers
Ans. A
