302. Antisyphonage pipe is fitted
A. at the end of septic tanks
B. on manholes
C. with a W.C. trap
D. at the beginning of sewer line.

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303. Chlorination of water is done for the removal of
A. bacterias
B. suspended solids
C. sediments
D. hardness.

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304. The effluent of a septic tank is
A. fit for discharge into any open drain
B. foul and contains dissolved and suspended solids
C. as good as that from a complete treatment
D. none of these.

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305. Dried sewage after treatinexit-is used as
A. fertilizer
B. building material
C. chemical for lowering B.O.D.
D. base material for paints.

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306.  In sewers the velocity of flow should not be
A. more than the self-cleansing velocity
B. less than the self-cleansing velocity
C. less than 10 m/sec
D. more than 20 in/sec.

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307. Self-cleansing velocity is
A. velocity at dry weather flow
B. velocity of water at flushing
C. velocity at which no accumulation remains in the drains
D. velocity of water in a pressure filter,

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308. Hydraulic mean radius is
A. mean radius of sewer
B. difference in heads between two points in circular pipes
C. mean of radii in a pipe line of varying cross-sections
D. cross-sectional area/wetted perimeter.

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