If the time of concentration is 9 minutes, then the intensity of rainfall according to British Ministry of Health formula will be
A). 4 mm/hr
B). 10 mm/hr
C). 20 mm/hr
D). 40 mm/hr
Dissolved oxygen in streams is
A). Maximum at noon
B). Minimum at noon
C). Maximum at midnight
D). Same throughout the day
For a country like India, where rainfall is mainly confined to one season, the suitable sewerage system will be
A). Separate system
B). Combined system
C). Partially combined system
D). Partially separate system
The percentage of chlorine in fresh bleaching powder is about
A). 10 to 15
B). 20 to 25
C). 30 to 35
D). 40 to 50
The percentage of filtered water, which is used for backwashing in rapid sand filters, is about
A). 0.2 to 0.4
B). 0.4 to 1.0
C). 2 to 4
D). 5 to 7