environmental engineering Mcqs
101. Dissolved oxygen in streams is______________?
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A. same throughout the day

B. maximum at midnight

C. maximum at noon

D. minimum at noon

102. The length of rectangular sedimentation tank should not be more than_______________?
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A. B

B. 4B

C. 2B

D. 8B

103. Sewerage system is designed for_______________?
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A. minimum flow only

B. maximum and minimum flow

C. maximum flow only

D. average flow only

104. The settling velocity of a particle in a sedimentation tank depends on__________________?
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A. depth of tank

B. surface area of tank

C. both depth and surface area of tank

D. none of the above

105. The velocity of flow does not depend on_______________?
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A. grade of sewer

B. hydraulic mean depth of sewer

C. roughness of sewer

D. length of sewer
106. Disinfection of water results in______________?
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A. removal of turbidity

B. removal of hardness

C. complete sterilisation

D. killing of disease bacteria
107. A pipe which is installed in the house drainage to preserve the water seal of traps is called______________?
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A. antisiphonage pipe

B. soil pipe

C. waste pipe

D. vent pipe

108. Sewage treatment units are normally designed for______________?
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A. 5-10 years

B. 15-20 years

C. 30-40 years

D. 40-50 years

109. For the same solid content, if the quantity of sludge with moisture content of 98% is X, then the quantity of sludge with moisture content of 96% will be__________________?
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A. 2X

B. X/2

C. X/4

D. X

110. If the coliform bacteria is present in a sample of water, then the coliform test to be conducted is_____________?
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A. confirmed coliform test

B. completed coliform test</strong>

C. correct answer is ?

D. presumptive coliform test
111. The rate of Alteration of pressure filters is_________________?
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A. greater than that of rapid sand filters

B. in between the filtration rate of slow sand filters and rapid sand filters

C. less than that of slow sand filters

D. equal to that of slow sand filters

112. Standard EDTA (ethylene diamine tetra acetic aciD. solution is used to determine the_______________?
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A. hardness in water

B. residual chlorine in water

C. turbidity in water

D. dissolved oxygen in water

113. The pipe which is used to carry the discharge from sanitary fittings like bath rooms, kitchens etc. is called_______________?
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A. antisiphonage pipe

B. waste pipe

C. vent pipe

D. soil pipe

114. The detention period in coagulation tanks is usually kept as_______________?
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A. 2 to 6 hours

B. 1 to 2 minutes

C. 2 to 6 days

D. 30 to 45 minutes

115. Most suitable section of sewer in separate sewage system is________________?
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A. rectangular section

B. circular section

C. modified egg shaped section

D. standard form of egg shaped sewer

116. The gas from sludge digestion tank is mainly composed of __________________?
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A. nitrogen

B. methane

C. hydrogen sulphide

D. carbon dioxide

117. The means of access for inspection and cleaning of sewer line is known as_______________?
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A. catch basin

B. drop manhole

C. manhole

D. inlet

118. Scour valves are provided ______________?
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A. at the foot of rising main along the slope to prevent back running of water

B. at every summit of rising mains

C. at street corners to control the flow of water

D. at every depression and dead ends to drain out the waste water that may collect there
119. The phenolic compounds in public water supply should not be more than_______________?
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A. 0.1 ppm

B. 0.01 ppm

C. 0.001 ppm

D. 0.0001 ppm

120. The self cleansing velocity for all sewers in India is usually_________________?
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A. 1.5 m/sec to 2.0 m/sec

B. 3.0 m/sec to 3.5 m/sec

C. less than 1.0 m/sec

D. 1.0 m/sec to 1.2 m/sec
121. The settling velocity of a particle in a sedimentation tank increases if______________?
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A. the depth of tank is decreased

B. particle size is decreased

C. none of the above

D. the surface area of tank is increased

122. The minimum dissolved oxygen which should always be present in water in order to save the aquatic life is______________?
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A. 4 ppm

B. 10 ppm

C. 40 ppm

D. 1 ppm

123. For a given discharge, the efficiency of sedimentation tank can be increased by______________?
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A. increasing the depth of tank

B. increasing the surface area of tank

C. decreasing the surface area of tank

D. decreasing the depth of tank

124. Period of cleaning of slow sand filters is about________________?
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A. 2-3 months

B. 24 48 hours

C. 1-2 year

D. 10-12 days

125. Sludge volume index is defined as the ratio of_______________?
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A. percentage of sludge by volume to percentage of total solids by weight

B. percentage of total solids by weight to percentage of sludge by volume

C. percentage of suspended solids by weight to percentage of sludge by volume

D. percentage of sludge by volume to percentage of suspended solids by weight
126. Which of the following values of pH represents a stronger acid?
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A. 2

B. 5

C. 10

D. 7

127. The relative stability of a sewage sample, whose dissolved oxygen is same as the total oxygen required to satisfy BOD, is______________?
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A. zero

B. 1

C. infinite

D. 100
128. Which of the following is not a water borne disease ?
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A. typhoid

B. maleria

C. dysentery

D. cholera

129. Assertion A : The consumption of water increases with increase in the distribution pressure. Reason R : Higher distribution pressure causes more loss and waste of water. Select your answer according to the coding system given below?
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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 the correct explanation of A

C. A is true but R is false

D. A is false but R is true

130. An egg shaped section of sewer________________?
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A. is more stable than circular section

B. is economical than circular section

C. is easy to construct

D. provides self cleansing velocity at low discharges
131. In a BOD test, 1.0 ml of raw sewage was diluted to 100 ml and the dissolved oxygen concentration of diluted sample at the beginning was 6 ppm and it was 4 ppm at the end of 5 day incubation at 20C. The BOD of raw sewage will be___________?
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A. 400 ppm

B. 100 ppm

C. 200 ppm

D. 300 ppm

132. The population of a town in three consecutive years are 5000, 7000 and 8400 respectively. The population of the town in the fourth consecutive year according to geometrical increase method is________________?
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A. 9500

B. 9800

C. 10920

D. 10100

133. The design discharge for the separate sewer system shall be taken as_____________?
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A. 3 x DWF

B. equal to dry weather flow (DWF)

C. 6xDWF

D. 2xDWF

134. The type of valve which is provided to control the flow of water in the distribution system at street corners and where the pipe lines intersect is_______________?
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A. sluice valve

B. check valve

C. safety valve

D. scour valve

135. If Biochemical oxygen demand (BOD. of a town is 20000 kg/day and BOD per capita per day is 0.05 kg, then population equivalent of town is_________________?
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A. 100000

B. 1000

C. 400000

D. 4000

136. Air binding phenomena in rapid sand filters occur due to_________________?
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A. higher turbidity in the effluent

B. excessive negative head

C. low temperature

D. mud ball formation

137. For normal sludge, the value of sludge index for Indian conditions is________________?
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A. 150 to 350

B. 50 to 150

C. 0 to 50

D. 350 to 500

138. In water treatment, rapid gravity filters are adopted to remove_______________?
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A. dissolved organic substances

B. dissolved solids and dissolved gases

C. bacteria and colloidal solids

D. floating solids and dissolved inorganic solids

139. The layout of distribution system in which water flows towards the outer periphery is_________________?
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A. radial system

B. ring system

C. dead end system

D. grid iron system

140. For satisfactory working of a sludge digestion unit, the pH range of digested sludge should be maintained as___________________?
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A. 10.5 to 12.0

B. 8.5 to 10.0

C. 4.5 to 6.0

D. 6.5 to 8.0
141. The detention period and overflow rate respectively for plain sedimentation as compared to sedimentation with coagulation are generally_______________?
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A. more and less

B. more and more

C. less and more

D. less and less

142. Which of the following chemical compounds can be used for dechlorination of water ?
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A. chloramines

B. carbon dioxide

C. sulphur dioxide

D. bleaching powder

143. The effect of increasing diameter of sewer on the self cleansing velocity is_____________?
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A. fluctuating

B. to decrease it

C. to increase it

D. nil

144. The detention period for oxidation ponds is usually kept as______________?
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A. 24 hours

B. 4-8 hours

C. 3 months

D. 10 to 15 days
145. Alkalinity in water is expressed as milli-grams per litre in terms of equivalent_______________?
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A. calcium carbonate

B. calcium hydroxide

C. sodium carbonate

D. magnesium carbonate

146. If the sewage contains grease and fatty oils, these are removed in_________________?
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A. grit chambers

B. sedimentation tanks

C. skimming tanks

D. detritus tanks

147. Which of the following sewers is preferred for combined system of sewage ?
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A. none of the above

B. circular sewer

C. rectangular sewer

D. egg shaped sewer