Water Supply Engineering

241. The head against which the motor works for lifting water, is

1. Maximum depth of water table below ground level
2. Maximum depression head
3. Velocity head
4. All the above

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242. The intake opening is generally covered by a screen to prevent entry of debris etc. and its level is kept

1. At the level of water of the source
2. At the bottom of water of the source
3. At about 2.5 m above the bottom
4. None of these

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243. The joint used for joining the plain ends of cast iron pipes, is

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

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244. The least thickness of class B cast iron (spun) pipe, is

1. 7.2 mm
2. 7.9 mm
3. 8.6 mm
4. 10 mm

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245. The level of underground water is called

1. Water level
2. Water table
3. Negative level
4. Invert level

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246. The lowest outlet sluice in a dam is provided

1. Below the dead storage
2. On the top level of dead storage
3. On the top level of useful storage
4. At the centre of the dam

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247. The main disadvantage of hard water, is

1. Greater soap consumption
2. Scaling of boilers
3. Corrosion and incrustation of pipes
4. All the above

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248. The main draw-back of centrifugal pump, is

1. Necessity of priming
2. Discharge from pump varies with the load of water
3. For high heads, efficiency is low up to 50%
4. All the above

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249. The main process to purify water by filtration, is

1. Mechanical straining
2. Flocculation and sedimentation
3. Biological metabolism
4. All the above

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250. The maximum depth of sedimentation tanks is limited to

1. 2 m
2. 3 m
3. 5 m
4. 6 m

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