MCQ
23981. The percentage of chlorine in fresh bleaching powder is-
20 to 25%
25 to 30%
30 to 35%
35 to 40%
23982. The coefficient of uniformity for slow sand filters is-
1.35
1.75
1.55
2.05
23983. The process of killing pathogenic bacterias from water is called-
sedimentation
coagulation
filteration
disinfection
23984. Slow sand filter is more efficient for the removal of-
bacteria
turbidity
odour
all of these
23985. The effluents from the septic tank are discharged into--
soak pit
drainage
oxidation pond
sewer
23986. The water from kitchens, bathrooms, wash basins is called-
sewage
raw sewage
sullage
none of this
23987. Rapid sand filter can remove turbidity from water upto an extent of-
15 to 25 ppm
25 to 35 ppm
35 to 40 ppm
40 to 50 ppm
23988. The secondary treatment of sewage is carried out by the use of-
screens
grit chambers
trickling filters
chlorinators
23989. The equipment used for cleaning the sewers easily is called-
gauge
claw
scoop
scraper
23990. The time of contact for chlorination should be at least-
5 minutes
20 minutes
1 hour
2 hours
23991. The minimum diameter of a manhole cover should be-
25cm
50cm
75cm
100cm
23992. Cleaning period for a rapid sand filter is taken as-
2 to 3 hours
2 to 3 days
2 to 3 weeks
2 to 3 months
23993. By lime soda process, hardness can be reduced to less than
50 ppm
75 ppm
150 ppm
100 ppm
23994. The cross-section recommended for separate system of sewerage is--
circular
rectangular
egg-shaped
none of these
23995. The aeration of water is done to remove--
colour
taste
odour
all of these
23996. The amount of chlorine used for plain b chlorination of water is about-
0.2 ppm
0.3 ppm
0.4 ppm
0.5 ppm
23997. Rapid sand filter can remove bacteria upto an extent of-
60 to 70%
70 to 80%
80 to 90%
90 to 99%
23998. The minimum size of a fire hydrant is--
5cm
10cm
15cm
20cm
23999. The human excreta is a ---waste.
dry
liquid
semi-liquid
solid
24000. The internal diameter of the sewer should not be less than-
15cm
25cm
50cm
75cm