Biochemical Oxygen Demand (B.O.D.) of safe drinking water must be________________?
Biochemical Oxygen Demand (B.O.D.) of safe drinking water must be________________?
A. nil
B. 5
C. 10
D. 15
E. 20
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Sunlight_________________ ?
Sunlight_________________ ?A. helps growth of bacterias
B. impedes growth of algae
C. increases dissolved oxygen content
D. reduces turbidityThe yield of a rapid gravity filter as compared to that of slow sand filter, is__________________?
The yield of a rapid gravity filter as compared to that of slow sand filter, is__________________?A. 10 times
B. 15 times
C. 20 times
D. 30 times
E. 35 timesAverage annual rainfall at any station is the average of annual rainfall over a period of________________?
Average annual rainfall at any station is the average of annual rainfall over a period of________________?A. 7 years
B. 14 years
C. 21 years
D. 28 years
E. 35 yearsAs per IS : 1172-1963, water required per head per day for average domestic purposes, is_______________?
As per IS : 1172-1963, water required per head per day for average domestic purposes, is_______________?A. 50 litres
B. 65 litres
C. 85 litres
D. 105 litres
E. 135 litresBy boiling water, hardness can be removed if it is due to_________________?
By boiling water, hardness can be removed if it is due to_________________?A. calcium sulphate
B. magnesium sulphate
C. calcium nitrate
D. calcium bicarbonate
E. none of theseThe maximum depth of sedimentation tanks is limited to________________?
The maximum depth of sedimentation tanks is limited to________________?A. 2 m
B. 3 m
C. 4 m
D. 5 m
E. 6 m