Water Supply Engineering

151. Normal values of overflow rate for sedimentation tanks using coagulants in litres/hr/m², generally range between

1. 250 to 500
2. 500 to 750
3. 750 to 1000
4. 1000 to 1250

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152. One degree of hardness of water means a content of salts of

1. 10.25 mg/litre
2. 12.25 mg/litre
3. 14.25 mg/litre
4. 16.25 mg/litre

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153. Open channels supported over trestles, are generally known as

1. Raised canals
2. Aqueducts
3. Siphons
4. Flumes

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154. P.V.C. pipes can withstand pressure bead of water upto

1. 25 m
2. 50 m
3. 75 m
4. 100 m

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155. Per capita demand of water is calculated in litres

1. Per person per day
2. Per person per month
3. Per person per year
4. None of these

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156. Perched aquifers are generally found

1. On the surface of the ground
2. Below the surface of the ground but above water table
3. Below the water table
4. All the above

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157. Perched aquifers generally occur

1. Below water table
2. Above water table
3. In aquicludes
4. In artesian aquifers

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158. Percussion drilling is unsuitable in

1. Unconsolidated sand
2. Unconsolidated gravel
3. Quick sand
4. Consolidated rocks

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159. Permanent hardness of water can be removed by

1. Adding alum
2. Adding lime
3. Adding chlorine
4. Zeolite process

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160. Pick up the correct statement from the following regarding radial flow centrifugal pumps:

1. These are provided with volute type or turbine type casings
2. In involute type of radial flow centrifugal pump, the impeller discharges into a gradually expanding spiral casing
3. The efficiency of turbine type of radial flow centrifugal pump, is always higher than that of volute type
4. All the above

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