MCQ
41. Biochemical Oxygen Demand (BOD) of safe drinking water must be-
0
50
10
100
42. The presence of hydrogen sulphide in water causes-
softening
acidity
alkalinity
bad taste
43. 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
44. The groundwater is generally free from impurities.
suspended
dissolved
45. The most important source of water for public water supply is-
lake
pond
river
sea
46. The maximum acidity in water will occur at a pH value of-
0
7
2
14
47. 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
48. Suspended impurities consist of-
iron
bacteria
chlorine
all of these
49. The most common cause of acidity in water is-
hydrogen
carbon dioxide
oxygen
all of theese
50. pH value is a symbol for ---concentration.
magnesium
hydrogen
calcium
sodium
51. 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
52. The maximum permissible temperature for domestic supply is-
5 to 10°C
10 to 15°C
15 to 20°C
20 to 25°C
53. The design period for a water supply project is taken as-
5 to 10 years
15 to 20 years
10 to 15 years
20 to 30 years
54. The max" permissible total solid content in water for domestic purposes should not exceed-
300 ppm
400 ppm
500 ppm
1000 ppm
55. The water bearing strata i.e. layers of sand, gravel etc. is called-
an aquifer
zone of saturation
an aquifuge
an aquiclude
56. When the pH value of water is more than 7, it represents--- water.
neutral
alkaline
acidic
solt
57. 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
58. The open wells or dug wells are also known as-
shallow wells
percolation wells
draw wells
all of these
59. The presence of bacteria in water causes-
hardness
diseases
alkalinity
bad taste
60. Sphere shaped bacteria are called-
spirilla
cocci
bacilli
trichobacteria