Water Supply Engineering

271. The pH value of water is kept slightly less than 7 so that hydrochloride ions may combine with ammonia ions to form

1. Mono-chloramine (NHCl)
2. Di-chloramine (NH₂Cl)
3. Nitrogen tri-chloramine (NCl₃)
4. All the above

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272. The population growth curve is

1. S-shaped curve
2. Parabolic curve
3. Circular curve
4. Straight line

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273. The population of a city in 2000 is 50,000. The average increase in population over last 8 decades is 7500 and average incremental increase during 8 decades is 750. The population of the city based on incremental method, in the year 2020 will be

1. 55000
2. 60500
3. 66500
4. 72500

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274. The population of a city in 2000 is 50,000. The average per decade of the previous records of population is 5000 and average percentage per decade is 20%. The population of the city based on geometrical increase method, in the year 2020 will be

1. 56000
2. 60000
3. 64000
4. 72000

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275. The prescribed hardness limit of potable water ranges between

1. 50 to 75 P.P.M.
2. 75 to 115 P.P.M.
3. 100 to 150 P.P.M.
4. 150 to 200 P.P.M.

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276. The process of passing water through beds of granular materials, is called

1. Screening
2. Sedimentation
3. Filtration
4. None of these

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277. The R.L. of ground water table on the sides of a valley is 1505 m whereas R.L. of the stream water is 1475 m. If 60° slope consists of pervious soil between R.L. 1485 m to 1500 m, the gravity spring may be expected at the point of reduced level

1. 1500 m
2. 1505 m
3. 1475 m
4. 1485 m

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278. The rate of silting in a reservoir

1. Is less in the beginning
2. Remains constant throughout
3. Is more in the beginning
4. is more in the beginning and reduces in the end

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279. The ratio of discharge and plan area of a continuous flow type settling tank, is known

1. Surface loading
2. Overflow
3. Overflow rate
4. All the above

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280. The ratio of maximum hourly consumption and average hourly consumption of the maximum day, is

1. 1.2
2. 1.5
3. 1.8
4. 2.7

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