281. Ventilating shafts are provided to a sewer line at every
A. 100 m
B. 150 m
C. 200 m
D. 300 m
282. Aerobic activity is maximum la in freshly produced sewage
A.in freshly produced sewage
B. at sewer pipes
C. in sewer treatment plants
D. none of these.
283. During putrifaction process of sewage the gas given off, is
A. carbon dioxide
B. hydrogen
C. ammonia
D. all the above.
284. Oxidation process results in the formation of
A. carbon dioxide
B. nitrates
C. sulphates
D. all the above.
285. Fresh sewage may become stale in
A. one hour
B. two to three hours
C. three to four hours
D. six hours.
286. Water content of sewage is about
A.90%
B.95%
C.99%
D. 9.9%.
287. For evaporation and measurement of settlable solids, the apparatus used, is
A. a jar
B. a breaker
C. a test tube
D. an Imhoff cone.
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