Water Supply Engineering

121. In a well planned city, the layout of distribution pipes generally adopted, is

1. Grid-iron system
2. Interlaced system
3. Reticulation system
4. All the above

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122. In an artesian aquifer, the draw downs in two observation wells at distances 100 m, and 200 m were found same after one hour and x hours respectively. The value of x, is

1. 2 hours
2. 4 hours
3. 9 hours
4. 16 hours

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123. In centrifugal pump installation,

1. Pump is properly primed before starting
2. The diameter of the pipe at inlet as well as at outlet, is kept smaller than the delivery pipe
3. The motor may burn out if it is started with empty delivery pipe and with open gate valve
4. All the above

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124. In distribution pipes, air valves are provided at

1. Lower points
2. Junction points
3. Higher points
4. Anywhere

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125. In distribution pipes, drain valves are provided at

1. Lower point
2. Higher point
3. Junction points
4. Anywhere

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126. In plain sedimentation tanks under normal conditions, impurities are removed upto

1. 0.6
2. 0.7
3. 0.8
4. 0.9

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127. In pressure supply mains, water hammer pressure is reduced by providing

1. Sluice valves
2. Air valves
3. Pressure relief valves
4. None of these

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128. In pumping stations, the type of joint generally used, is

1. Socket and spigot joint
2. Flanged joint
3. Expansion joint
4. Dresser coupling joint

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129. In rapid sand filters the ratio of length and diameter of the lateral, should not be greater than

1. 10
2. 15
3. 20
4. 25

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130. In slow sand filters, the turbidity of raw water can be removed only up to

1. 60 mg/litre
2. 75 mg/litre
3. 100 gm/litre
4. 150 mg/litre

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