MCQ
16281. Biochemical Oxygen Demand (BOD) of safe drinking water must be-
0
50
10
100
16282. The presence of hydrogen sulphide in water causes-
softening
acidity
alkalinity
bad taste
16283. The most common cause of acidity in water is-
hydrogen
carbon dioxide
oxygen
all of theese
16284. Slow sand filter is more efficient for the removal of-
bacteria
turbidity
odour
all of these
16285. 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
16286. The maximum acidity in water will occur at a pH value of-
0
7
2
14
16287. 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
16288. 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
16289. The velocity of flow in any sedimentation tank should not exceed-
0.05mm/s
5mm/s
0.5mm/s
50mm/s
16290. 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
16291. 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
16292. Rapid sand filter can remove bacteria upto an extent of-
60 to 70%
70 to 80%
80 to 90%
90 to 99%
16293. The coefficient of uniformity for slow sand filters is-
1.35
1.75
1.55
2.05
16294. The max" permissible total solid content in water for domestic purposes should not exceed-
300 ppm
400 ppm
500 ppm
1000 ppm
16295. pH value is a symbol for ---concentration.
magnesium
hydrogen
calcium
sodium
16296. When the pH value of water is more than 7, it represents--- water.
neutral
alkaline
acidic
solt
16297. The maximum permissible colour for domestic supplies, on platinum cobalt scale is-
5 to 10 ppm
10 to 20 ppm
20 to 30 ppm
30 to 40 ppm
16298. The maximum permissible temperature for domestic supply is-
5 to 10°C
10 to 15°C
15 to 20°C
20 to 25°C
16299. Sphere shaped bacteria are called-
spirilla
cocci
bacilli
trichobacteria
16300. The maximum permissible turbidity for domestic supplies, on silica scale is-
5 to 10 ppm
20 to 30 ppm
10 to 20 ppm
30 to 40 ppm