1. After cleaning a slow sand filter, the filtered water is not used for
Correct : D. 24 hours to 36 hours
2. The efficiency of sedimentation tank does not depend upon
Correct : D. Velocity of water
3. Velocity of flow of water in plain sedimentation water tank, is normally kept
Correct : D. 30 cm/minute
4. The depth of the water table at a place is 45 m below the general ground level. To lift water
from a deep tube well in such a locality, the type of pump to be installed is
Correct : C. Deep well turbine pump
5. In a well planned city, the layout of distribution pipes generally adopted, is
Correct : D. All the above
6. Pick up the incorrect statement from the following:
Correct : D. Level of water table remains stationary
7. Pick up the incorrect statement from the following:
Correct : C. In strainer type wells, area of flow depends upon the length of the strainer pipe
8. As per IS : 1172-1963, water required per head per day for average domestic purposes, is
Correct : D. 135 litres
9. The duration of contact of chlorine with water before it is served to the first consumer, should
be at least
Correct : C. 20 to 30 minutes
10. Water supply system includes
Correct : D. Entire arrangement from source to distribution
11. The maximum pressure to which a pipe is subjected to during its operation, is known
Correct : A. Working pressure
12. For the same draw down in two observations wells at distances r1 and r2, the times after start
of pumping are t1 and t2 hours respectively. The relation which holds good is
Correct : B. t2 = (r2/r1)² × t1
13. A slow sand filter is cleaned if its filter head is higher than
Correct : D. 70 cm to 120 cm
14. The intake opening is generally covered by a screen to prevent entry of debris etc. and its level
is kept
Correct : C. At about 2.5 m above the bottom
15. If four fires break out in a city of population 40 lakhs and if each hydrant has three streams and
duration of each fire is four hours, the total quantity of water required, is
Correct : B. 2880 kilo litres
16. Steel pipe are
Correct : D. Likely to last 100 years under ordinary conditions
17. When gravity and pumping systems of water distribution are adopted, the type of distribution
reservoir, is
Correct : A. Elevated tank
18. The force which develops in a pressure conduit supported on trestles, is
Correct : D. Flexural stress
19. Standard unit of turbidity of water is in one litre of distilled water, one milligram of finely
divided
Correct : A. Silica
20. For complete stabilisation of organic matter in polluted water, it takes
Correct : D. 30 days
21. If intensity of rainfall in cm per hour is I, percentage coefficient of run-off is P, area of catchment
in square kilometres is A, the total run-off Q, is given by
Correct : C. Q = 2.758 × 103× API
22. Shales are
Correct : D. Porous but not permeable
23. The best process of disinfection of public water supply, is by
Correct : B. Chlorination
24. The dilution ratio at which the odour is hardly detectable is generally called threshold odour
number and for public supplies it should not exceed
Correct : A. 3
25. Surge tanks are used
Correct : D. To guard against water hammer
26. Normal values of overflow rate for plain sedimentation tanks in litres/hr/m2, generally range between
Correct : C. 500 to 750
27. P.V.C. pipes can withstand pressure bead of water upto
Correct : D. 100 m
28. Most commonly used pump for lifting water in water supply mains, is
Correct : A. Axial flow pump
29. The fire demand for a city of 50,000 populations, according to Godrich formula, is
Correct : C. 44 mld
30. If V is total consumption of water in litres for a population of N individuals, per capita
consumption or water allowance for the water supply Q, is given by
Correct : C. Q = V/265N
31. For controlling algae, the most commonly used chemical, is
Correct : A. Copper sulphate
32. The storage capacity of a reservoir may be divided into three zones. The lowest zone is
Correct : A. Dead storage
33. Economic height of a dam is the height corresponding to which
Correct : A. Cost of the dam per unit of storage is minimum
34. For maximum alkalinity of water, pH value should be
Correct : D. 14
35. The efficiency of a pumping set, is generally assumed
Correct : D. 65 %
36. The population growth curve is
Correct : A. S-shaped curve
37. The fire demand for ascertaining the empirical formula 1136.5 [(P/10) + 10] known as
Correct : C. Freeman formula
38. The bacterias which may survive with or without free oxygen, are called
Correct : C. Facultative bacteria's
39. Aeration of water is done to remove
Correct : A. Odour
40. The maximum pressure to which cast iron pipes may be subjected to, is
Correct : C. 7 kg/cm2
41. Water may not contain much impurity if its source is
Correct : D. Spring along hill slopes
42. If p is total internal pressure, d is diameter of pressure conduit and t is thickness of conduit, the
Hoop's stress is
Correct : C. dp/2t
43. Turbidity of water is expressed
Correct : A. In ppm
44. In plain sedimentation tanks under normal conditions, impurities are removed upto
Correct : B. 70 %
45. In slow sand filters, the turbidity of raw water can be removed only up to
Correct : A. 60 mg/litre
46. Pressure relief valves are provided in water mains
Correct : D. All the above
47. Biochemical Oxygen Demand (B.O.D.) of safe drinking water must be
Correct : A. Nil
48. At break point of chlorination,
Correct : D. Residual chlorine reappears
49. The capability of a soil mass of full width and depth to transmit water, is known
Correct : B. Permeability
50. By boiling water, hardness can be removed if it is due to
Correct : D. Calcium bicarbonate
51. Percussion drilling is unsuitable in
Correct : D. Consolidated rocks
52. Rapid gravity filters can remove bacterial impurities up to a maximum of
Correct : D. 80 %
53. Continuous flow of water can be expected from
Correct : C. Artesian springs
54. Reciprocating pumps
Correct : A. Are not suitable for variable heads
55. Low turbidity of water is detected by
Correct : C. Baylis turbidimeter
56. Silt storage is the same as
Correct : A. Dead storage
57. The type of pipe commonly used in water supply distribution schemes, is
Correct : C. Cast iron pipes
58. Pick up the incorrect statement from the following. The source of surface water is from
Correct : C. Springs
59. The discharge Q = 2𝜋𝐾𝐻𝑆/2.3 log10 (R/rw) for the confined tube well is obtained from
Correct : D. Dupuits formula
60. m and n are monsoon duration factor and catchment factor respectively. If P is yearly rainfall in cm, runoff can be calculated by
Correct : A. Velocity area method
61. In a rapid gravity filter
Correct : C. Raw water passed through coagulation tank is supplied
62. The maximum permissible nitrites in public water supplies, is
Correct : A. Nil
63. Most commonly used section in grade aqueducts, is
Correct : B. Rectangular
64. The most important and widely used tube well in India, is
Correct : A. Strainer well
65. Critical time for developing a water hammer, is the time required for
Correct : C. The wave to travel from the valve to the reservoir and back
66. Bacterias which can survive with or without free oxygen, are known
Correct : C. Facultative bacterias
67. The standard B.O.D. at 20°C, is taken for the consumption in
Correct : D. 5 days
68. Distribution of wash water is provided in
Correct : C. Rapid gravity filter
69. If P is population of a city in thousands and Q is fire demand in litres per minute, for proper
estimate of water, the Empirical formula Q = 1135 [(P/5) + 10] is suggested by
Correct : B. Freeman
70. During treatment of water, sedimentation is done
Correct : A. Before filtration
71. The ratio of the maximum daily consumption to the average daily demand, is
Correct : D. 1.8
72. From the surface of reservoir, evaporation may be minimized by sprinkling
Correct : C. Acetyl alcohol
73. The transitional middle portion of a logistic curve follows
Correct : D. A constant rate
74. For plain chlorination of water, the quantity of chlorine used, is
Correct : D. 0.5 mg/litre
75. In distribution pipes, air valves are provided at
Correct : C. Higher points
76. Manholes along the mains from the source to a city are provided at 500 m intervals in
Correct : D. All the above
77. The maximum permissible colour for domestic supplies based on cobalt scale, is
Correct : D. 20 ppm
78. Increase in population of a rapidly growing city, may be estimated by
Correct : B. Geometrical method
79. Per capita demand of water is calculated in litres
Correct : A. Per person per day
80. Hard water for public water supply is discarded because
Correct : A. ) It consumes more soap
81. Pick up the incorrect statement from the following:
Correct : C. Iron salts can be used over a limited range of pH values
82. Asbestos pipes are
Correct : D. All the above
83. A strainer type well sunk through three previous layers intervened by three impervious
aquicludes, draws water from