MCQ
4041. When the pH value of water is more than 7, it represents--- water.
neutral
alkaline
acidic
solt
4042. Rapid sand filter can remove bacteria upto an extent of-
60 to 70%
70 to 80%
80 to 90%
90 to 99%
4043. The process of killing pathogenic bacterias from water is called-
sedimentation
coagulation
filteration
disinfection
4044. pH value is a symbol for ---concentration.
magnesium
hydrogen
calcium
sodium
4045. 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
4046. 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
4047. The max" permissible total solid content in water for domestic purposes should not exceed-
300 ppm
400 ppm
500 ppm
1000 ppm
4048. The velocity of flow in any sedimentation tank should not exceed-
0.05mm/s
5mm/s
0.5mm/s
50mm/s
4049. 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
4050. The most common cause of acidity in water is-
hydrogen
carbon dioxide
oxygen
all of theese
4051. 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
4052. 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
4053. The coefficient of uniformity for slow sand filters is-
1.35
1.75
1.55
2.05
4054. The maximum acidity in water will occur at a pH value of-
0
7
2
14
4055. 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
4056. 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
4057. Sphere shaped bacteria are called-
spirilla
cocci
bacilli
trichobacteria
4058. Slow sand filter is more efficient for the removal of-
bacteria
turbidity
odour
all of these
4059. Biochemical Oxygen Demand (BOD) of safe drinking water must be-
0
50
10
100
4060. The time of contact for chlorination should be at least-
5 minutes
20 minutes
1 hour
2 hours