Water Supply Engineering

171. Plain chlorination is used for water

1. Obtained from clear lakes
2. Consumed during emergencies
3. Supplies to armies during war
4. All the above

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172. Pressure exerted at 90° bend in a pipe of cross-sectional area A and carrying water with a velocity V under a pressure p, is

1. [pA + (w/g) AV]
2. 2 [pA + (w/g) AV²]
3. pA + (w/g) AV²]
4. pA + (w/g) A²V]

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173. Pressure relief valves are provided in water mains

1. To reduce the pressure
2. At low points
3. Upstream of sluice
4. All the above

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174. Property of earth to allow water to pass through it, is known as

1. Perviousness
2. Porosity
3. Permeability
4. Transmissibility

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175. Q is the discharge from an unconfined tube well with depression head s through its pipe of radius rw. If the radius of influence is R, the length of the required strainer, is

1. 2.3Q log₁₀ (R/rw)²
2. 2.3Q log_e (R/rw)²
3. 2.3Q log_e (R/rw)/2πKs
4. 2.3Q log₁₀ (R/rw)/2πKs

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176. Quality of water is said to be good if it is

1. Free from suspended matter
2. Colourless
3. Free from pathogenic organism
4. All the above

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177. Rapid gravity filter can only remove turbidity of water upto

1. 15 to 25 gm/litre
2. 25 to 30 gm/litre
3. 30 to 35 cm/litre
4. 35 to 40 gm/litre

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178. Rapid gravity filters

1. Were developed by G.W. Fuller
2. Make use of coarser sand with effective size as 0.5 mm
3. Yield as high as 30 times the yield of slow sand filters
4. All the above

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179. Rapid gravity filters can remove bacterial impurities up to a maximum of

1. 0.5
2. 0.6
3. 0.7
4. 0.8

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180. Rapid sand filter

1. Should be preceded by coagulation and sedimentation
2. Uses rapid sand as filter media
3. Is used after slow sand filtering has been done
4. Can combine disinfection also

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