environmental engineering MCQs – Page 7

Practise focused environmental engineering questions with marked answers for exam preparation and subject revision.

environmental engineering Mcqs

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

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