Practice Test: Question Set - 17
1. De-chlorination is followed by
- (A) Post-chlorination
- (B) Pre-chlorination
- (C) Double-chlorination
- (D) Super-chlorination
2. The least thickness of class B cast iron (spun) pipe, is
- (A) 7.2
mm
- (B) 7.9
mm
- (C) 8.6
mm
- (D) 10
mm
3. Water having pH value as 6, is
- (A) Alkaline
- (B) Acidic
- (C) Neutral
- (D) None
of these
4. Maximum permissible color for domestic water supplies, based on Cobalt scale, is
- (A) 5 P.P.M.
- (B) 10 P.P.M.
- (C) 15 P.P.M.
- (D) 20 P.P.M.
5. The main process to purify water by filtration, is
- (A) Mechanical
straining
- (B) Flocculation
and sedimentation
- (C) Biological
metabolism
- (D) All
the above
6. The approximate diameter of a water mains for supplying 7.2 mld with a velocity 1.2 m/sec, is
- (A) 24 cm
- (B) 26 cm
- (C) 28 cm
- (D) 30 cm
7. For least effect on the water table, the tube wells must be dug one in every
- (A) 0.5 sq km
- (B) 0.75 sq km
- (C) 1.0 sq km
- (D) 1.5 sq km
8. An area is declared drought affected if its mean rainfall is less than
- (A) 50 %
- (B) 60 %
- (C) 75 %
- (D) 85 %
9. A circular gravity aqueduct is not generally preferred to because of
- (A) Its
maximum hydraulic mean depth
- (B) Maximum
area per unit of wetted perimeter
- (C) Minimum
cost of construction
- (D) Its
proper support on the ground
10. Efficiency of removing bacterias from raw water by a slow sand filter, is
- (A) 80% to 81%
- (B) 85% to 86%
- (C) 90% to 97%
- (D) 98% to 99%
11. A high velocity of wash water is required for
- (A) Rapid
gravity filter with strainers
- (B) Rapid
gravity filter without strainers
- (C) Slow
sand filter with strainers
- (D) Slow
sand filter without strainers
12. In a reservoir the average volume of sediment deposition is 0.15 million cubic per year. If the dead storage and total capacity of the reservoir are 8 million cubic meters and 36 million cubic meters respectively,
- (A) The
reservoir will theoretically be silted in 240 years
- (B) The
reservoir will start reducing after 60 years
- (C) Both (a) and
(b)
- (D) Neither (a)
nor (b)
13. 135 liters of water per person per day, is provided in
- (A) Nurses
homes
- (B) Hostels
- (C) Residential
schools
- (D) All the
above
14. Pick up the correct statement from the following:
- (A) Excess
quantities of iron and manganese in water, cause discoloration of clothes
- (B) Lead and
barium salts have toxic effect
- (C) Higher
copper content affects the lungs
- (D) All the
above
15. Disinfection of drinking water is done to remove
- (A) Turbidity
- (B) Odour
- (C) Color
- (D) Bacterias
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