MCQ
21001. The most common cause of acidity in water is-
hydrogen
carbon dioxide
oxygen
all of theese
21002. The total count of bacteria per cubic centimeter for domestic purposes varies from-
0 to 100
150 to 200
100 to 150
200 to 250
21003. Rapid sand filter can remove bacteria upto an extent of-
60 to 70%
70 to 80%
80 to 90%
90 to 99%
21004. 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
21005. Sphere shaped bacteria are called-
spirilla
cocci
bacilli
trichobacteria
21006. The maximum acidity in water will occur at a pH value of-
0
7
2
14
21007. The percentage of chlorine in fresh bleaching powder is-
20 to 25%
25 to 30%
30 to 35%
35 to 40%
21008. Slow sand filter is more efficient for the removal of-
bacteria
turbidity
odour
all of these
21009. The velocity of flow in any sedimentation tank should not exceed-
0.05mm/s
5mm/s
0.5mm/s
50mm/s
21010. Biochemical Oxygen Demand (BOD) of safe drinking water must be-
0
50
10
100
21011. The effective size of sand particles for slow sand filters varies from- 0.3 to 0.35mm 0.35 to 0.5mm 0.5 to 0.65mm 0.65 to 0.75mm
0.3 to 0.35mm
0.35 to 0.5mm
0.5 to 0.65mm
0.65 to 0.75mm
21012. The coefficient of uniformity for slow sand filters is-
1.35
1.75
1.55
2.05
21013. pH value is a symbol for ---concentration.
magnesium
hydrogen
calcium
sodium
21014. The pH value of water for public supplies is limited from-
2.5 to 6.5
8 to 10.5
6.5 to 8.5
10.5 to 15
21015. 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
21016. 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
21017. The process of killing pathogenic bacterias from water is called-
sedimentation
coagulation
filteration
disinfection
21018. The time of contact for chlorination should be at least-
5 minutes
20 minutes
1 hour
2 hours
21019. The detention time for an ordinary plain sedimentation tank is-
1 to 2 hours
6 to 8 hours
2 to 4 hours
20 to 24 hours
21020. When the pH value of water is more than 7, it represents--- water.
neutral
alkaline
acidic
solt