76. The commonly used material for water supply pipes, which has the properties of being strong, not easily corroded and long life but is heavy and brittle is
a) steel
b) cast iron
c) copper
d) reinforced cement concrete
Ans:b
77. Hardy cross method of analysis of distribution system
i) involves successive trials
ii) takes economic aspects into account
iii) is time consuming
The correct answer is
a) only (i)
b) (i)and(ii)
c) (i) and (iii)
d) all are correct
Ans:c
78. The method of analysis of distribution system in which the domestic supply is neglected and fire demand is considered is
a) circle method
b) equivalent pipe method
c) electrical analysis method
d) Hardy cross method
Ans:a
79. Which of the following methods of analysis of water distribution system is most suitable for long and narrow pipe system ?
a) circle method
b) equivalent pipe method
c) Hardy cross method
d) electrical analysis method
Ans:b
80. The type of valve which is provided to control the flow of water in the distribution system at street corners and where the pipe lines intersect is
a) check valve
b) sluice valve
c) safety valve
d) scour valve
Ans:b
81. The type of valve which allows water to flow in one direction but prevents its flow in the reverse direction is
a) reflux valve
b) sluice valve
c) air relief valve
d) pressure relief valve
Ans:a
82. Scour valves are provided
a) at street corners to control the flow of water
b) at every depression and dead ends to drain out the waste water that may collect there
c) at the foot of rising main along the slope to prevent back running of water
d) at every summit of rising mains
Ans:b
83. A sewer that receives the discharge of a number of house sewers is called
a) house sewer
b) lateral sewer
c) intercepting sewer
d) submain sewer
Ans:b
84. A pipe conveying sewage from plumbing system of a single building to common sewer or point of immediate disposal is called
a) house sewer
b) lateral sewer
c) main sewer
d) submain sewer
Ans:a
85. 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
Ans:a
86. Average rate of water consumption perhead per day as per Indian Standard is
a) 100 litres
b) 135 litres
c) 165 litres
d) 200 litres
Ans:b
87. Sewerage system is usually designed for
a) 10 years
b) 25 years
c) 50 years
d) 75 years
Ans:b
88. Which of the following sewers is preferred for combined system of sewage ?
a) circular sewer
b) egg shaped sewer
c) rectangular sewer
d) none of the above
Ans:b
89. The suitable system of sanitation for area of distributed rainfall throughout the year with less intensity is
a) separate system
b) combined system
c) partially separate system
d) partially combined system
Ans:b
90. The water carriage system of collection of waste product
a) is cheaper in initial cost than dry conservancy system
b) requires treatment before disposal
c) creates hygenic problem
d) all of the above
Ans:b
91. 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) lOmm/hr
c) 20 mm/hr
d) 40 mm/hr
Ans:d
92. The time of concentration is defined as
a) the time taken by rainfall water to run from most distant point of water shed to the inlet of sewer
b) the time required for flow of water in sewer to the point under consideration
c) sum of (a) and (b)
d) difference of (a) and (b)
Ans:c
93. The specific gravity of sewage is
a) much greater than 1
b) slightly less than 1
c) equal to 1
d) slightly greater than 1
Ans:d
94. The self cleansing velocity for all sewers in India is usually
a) less than 1.0 m/sec
b) 1.0 m/sec to 1.2 m/sec
c) 1.5 m/sec to 2.0 m/sec
d) 3.0 m/sec to 3.5 m/sec
Ans:b
95. The slope of sewer shall be
a) given in the direction of natural slope of ground
b) given in the direction opposite to natural slope of ground
c) zero
d) steeper than 1 in 20
Ans:a
96. The design discharge for the separate sewer system shall be taken as
a) equal to dry weather flow (DWF)
b) 2xDWF
c) 3 x DWF
d) 6xDWF
Ans:d
97. The design discharge for the combined sewer system shall be taken as
a) equal to rainfall
b) rainfall + DWF
c) rainfall + 2 DWF
d) rainfall + 6 DWF
Ans:c
98. The minimum and maximum diameters of sewers shall preferably be
a) 15 cm and 100 cm
b) 15 cm and 300 cm
c) 30 cm and 450 cm
d) 60 cm and 300cm
Ans:b
99. The main disadvantage of cement concrete sewers is
a) less strength
b) difficulty in construction
c) difficulty in transportation due to heavy weight
d) less life
Ans:c
100. Most suitable section of sewer in separate sewage system is
a) rectangular section
b) circular section
c) standard form of egg shaped sewer
d) modified egg shaped section
Ans:b