A. 4-8 hours
B. 24 hours
C. 10 to 15 days
D. 3 months
✅ The correct answer is option C.
Environmental Engineering MCQs
102. As compared to cast iron pipes, steel pipes are______________?
A. heavier
B. stronger
C. costlier
D. less susceptible to corrosion
✅ The correct answer is option B.
103. Alum as a coagulant is found to be most effective when pH range of water is______________?
A. 2 to 4
B. 4 to 6
C. 6 to 8
D. 8 to 10
✅ The correct answer is option C.
104. Sewage treatment units are normally designed for______________?
A. 5-10 years
B. 15-20 years
C. 30-40 years
D. 40-50 years
✅ The correct answer is option B.
105. Sewage treatment units are designed for_______________?
A. maximum flow only
B. minimum flow only
C. average flow only
D. maximum and minimum flow
✅ The correct answer is option C.
106. For normal sludge, the value of sludge index for Indian conditions is________________?
A. 0 to 50
B. 50 to 150
C. 150 to 350
D. 350 to 500
✅ The correct answer is option C.
107. 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________________?
A. 9500
B. 9800
C. 10100
D. 10920
✅ The correct answer is option D.
108. Facultative bacteria are able to work in________________?
A. presence of oxygen only
B. absence of oxygen only
C. presence as well as in absence of oxygen
D. presence of water
✅ The correct answer is option C.
109. The specific gravity of sewage is_______________?
A. much greater than 1
B. slightly less than 1
C. equal to 1
D. slightly greater than 1
✅ The correct answer is option D.
110. Activated carbon is used for_____________?
A. disinfection
B. removing hardness
C. removing odours
D. removing corrosiveness
✅ The correct answer is option C.