239. Hard water for public water supply is discarded because
A. it consumes more soap
B. it contains lot of turbidity
C. it contains pathogenic bacterias
D. it possesses bad taste and odour
240. The temporary hardness of water can be removed by
A. boiling ,
B. adding lime
C. adding alum ,( d) filtration
241. The permissible pH value for public water supplies may range between
A. 4.5 to 5.5
B. 5.5 to 6.5
C. 6.5 to 8.5
D. 8.5 to 10.5
242. The maximum permissible chloride content in treated water of public water supplies should not exceed
A. 50 P.P.M.
B. 100 P.P.M.
C. 150 P.P.M.
D. 250 P.P.M.
243. The prescribed hardness limit of potable water ranges between
A. 50 to 75 P.P.M.
B. 75 to 115 P.P.M.
C. 100 to 150 P.P.M.
D. 150 to 200 P.P.M.
244. The maximum permissible nitrites in public water supplies, is
B. 0.5 P.P.M.
C. 1.0. P.P.M.
D. 1.5 P.P.M.
245. Biochemical Oxygen Demand (B.O.D.) of safe drinking water must be
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