337.  The following are the activities involved in the chemical coagulation sedimentation plant of water supplies 1. Flocculation 2. Feeding the Coagulation 3. Mixing the coagulation in flocculated water 4. Settling sedimentation tank The correct sequence of the activities is
A.1,2,3,4
B.4.3.1.2
C.2,3,1,4
D.3,4,2,1

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338.  Which one of the following processes does not contribute in the process of filtration :
A. Mechanical straining
B. Flocculation and sedimentation
C. Biological metabolism
D. None of these.

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339.  The filter sand should not loose more than .. of its weight after being placed in hydrochloric acid for 24 hours
A.2%
B.3%
C.5%
D.10%

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340.  The filter sludge if disposed in natural drainage channels, may cause
A. siltation of the channels
B. atmospheric pollution
C. pollution of the channels
D. all the above.

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341.  The operational troubles in rapid gravity filtes may be caused due to
A. air bending phenomenon
B. formation of mud balls
C. cracking of filters
D. All the above.

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342.  The treated water obtained from
A. slow sand filters is better than that obtained from rapid gravity filters
B. rapid gravity filters is better than that obtained from slow sand filters
C. both slow sand filters and rapid gravity filters are of same quality
D. None of these.

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343.  Which one of the following is the most destructive disinfecting agent :
A. Hypochlorous acid (HOC1)
B. Hypochlorite ions (OC1)
C. Chlorine (C12)
D. Hydrochloride acid (HC1)

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