274. The laying of sewers is done with
A. magnetic compass
B. theodolite
C. level
D. clinometers

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275. For drainage pipes in buildings the test applied before putting them to use, is
A. water test
B. smoke test
C.A straightness test
D. all the above.

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276. The gas which may cause explosion in sewers, is
A. carbondioidde
B. methane
C. ammonia
D. carbon monoxide.

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277. Fresh sewage is generally
A. alkaline
B. acidic
C. highly decomposed
D. a source of objectionable odour.

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278. For large sewers, maximum distance between manholes may be
A. 50 m
B. 100 m
C. 200 m
D. 300 m

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279.  The minimum diameter of an opening of a manhole should be
A. 25 ni
B.? 50 M
C. 75 m
D. 100 m

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280.  At the junction of sewers
A. top of smaller sewer is kept lower
B. top of larger sewer is kept lower
C. tops of both the sewers are at the same level
D. none of these.

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