274. The maximum permitted loss of head in a rapid sand filter, is
A. 1 m
B. 2 m
C. 3 m
D. 4 m
275. In a rapid sand filter, air binding is caused due to excessive
A. negative pressure
B. pressure
C. turbidity
D. water pressure
276. Mud balls may be removed by
A. breaking and washing
B. washing the filter with a solution of caustic soda
C. removing, cleaning and replacing the damaged sand
D. all the above,
277. Rapid gravity filters can remove bacterial impurities up to a maximum of
A.50%
B.60%
C.70%
D.80%
278. Rapid gravity filter can only remove turbidity of water upto
A. 15 to 25 gm/litre
B. 25 to 30 gm/litre
C. 30 to 35 cm/litre
D. 35 to 40 gm/litre
279. E. Coli bacterias die in water having pH greater than
A.5.5
B.6.5
C.7.5
D. 9.5.
280. The most ideal disinfectant used for drinking water throughout the world, is
A. alum
B. lime
C. chlorine
D. nitrogen
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