### Civil Engineering - Water Supply Engineering MCQs Part 7

1. Raw water treated with only chlorine, is known as

A.
plain chlorination
B.
pre-chlorination
C.
first-chlorination
D.
de-chlorination
E.
none of these.

2. The level of underground water is called

A.
water level
B.
water table
C.
negative level
D.
invert level.

3. Per capita demand of water is calculated in litres

A.
per person per day
B.
per person per month
C.
per person per year
D.
none of these.

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

A.
25 m
B.
50 m
C.
75 m
D.
100 m
E.
125 m.

5. 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

A.
55,000
B.
60,500
C.
66,500
D.
72,500
E.
76,500

6. Air inlet valve in water mains, is generally provided at

A. summit of the pipe
B. upstream of sluice valve
C. down stream of sluice valve
D. valley of the pipe
E. both (a) and (c) of above.

7. The duration of contact of chlorine with water before it is served to the first consumer, should be at least

A. 10 to 15 minutes
B. 15 to 20 minutes
C. 20 to 30 minutes
D. 30 to 40 minutes
E. one hour.

8. The diameter of pipes in bath rooms and lavatories in domestic water supply, is

A. 6 mm
B. 12 mm
C. 18 mm
D. 24 mm.

9. Pick up the incorrect statement from the following :

A. The water entering the slow sand filters should be treated by 9.386 coagulants
B. The depth of water on the filter should be twice the depth of the filter sand
C. When the filter head is 0.75 times the depth of filter sand, the water obtained is purest
D. The cleaning of slow sand filters is done by back washing
E. All the above.

10. m and n are monsoon duration factor and catchment factor respectively. If P is yearly rainfall in cm, runoff can be calculated by

A. velocity area method
B. weir or spillway method
C. use of venturi-meter
D. using power plant consumption
E. none of these.

11. Most important method for calculating discharge for planning a water supply project, is

A. velocity area method
B. weir or spillway method
C. use of venturi-meter
D. using power plant consumption
E. none of these.

12. Alkalinity in water may be caused due to

A. calcium and magnesium bicarbonates
B. sodium carbonate
C. potassium carbonate
D. calcium hydroxide
E. all the above.

13. Open channels supported over tres-les, are generally known as

A. raised canals
B. acqueducts
C. syphons
D. flumes.

14. For least effect on the water table, the tube wells must be dug one in every

A. 0.5 sq km
B. 0.75 sq km
C. 1.0 sq km
D. 1.25 sq km
E. 1.5 sq km.

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

A. 60%
B. 70%
C. 80%
D. 90%.

16. Pick up the correct statement from the following :

A. Due to boiling, the bacterias present in water can be destroyed
B. Lime may be used for softening hard water
C. Excess lime when added to water, raises the pH value of water
D. the bacterias do not survive in water having pH value exceeding 9.5
E. All the above.

17. For the same draw down in two observations wells at distances r1 and r2, the times after start of pumping are t1 and t2 hours respectively. The relation which holds good is

A.
B.
C.
D.
E. none of these.

18. The valve fitted closely in a recess against an opening in a pipe, is generally

A. wedge shaped circular disc
B. spherical disc
C. parallelopiped disc
D. conical shaped circular disc.

19. For calculation of economical diameter D of a pipe in metres for a discharge Q to be pumped in cumecs, Lea suggested the empirical formula

A. D = 0.22 Q
B. D = 1.22 Q
C. D = 2.22 Q
D. D = 3.22 Q
E. D = 1.33 Q.

20. S1 and S2 are the draw downs in an observation well at times t1 and t2 after pumping. For discharge Q and coefficient of transmissibility T, the relationship, is

A.
B.
C.
D.

21. An ideal sand for filters should be

A. free from dirt and other impurities
B. uniform in nature and size
C. hard and resistant
D. all the above.

22. The maximum non-verticality of the bore of a well 200 m deep, may be permitted up to

A. 25 cm
B. 50 cm
C. 75 cm
D. 100 cm
E. 150 cm.

23. By adding 1 ml of orthotolidine solution to 100 ml chlorinated water taken after contact period, the residual chlorine makes the colour of solution

A. yellowish
B. greenish
C. bluish
D. reddish
E. violet.

24. From the surface of reservoir, evaporation may be minimised by sprinkling

A. Spirit
B. Hydrochloric acid
C. Cetyl alcohol
D. Methane
E. None of these.

25. Gravity conduits are generally in the form of

A. canals
B. flumes
C. aqueduct
D. tunnels
E. all the above.

26. Pick up the correct statement from the following :

A. The ratio of the total sediment deposited in the reservoir to the total sediment flowing in the river, is called trap efficiency
B. The ratio of the reservoir capacity to the total inflow of water in it, is generally called capacity inflow ratio
C. Small capacity reservoirs on large rivers generally, silt less
D. Large capacity reservoirs on small rivers generally silt more
E. All the above.

27. Pressure relief valves are provided in water mains

A. to reduce the pressure
B. at low points
C. upstream of sluice
D. all the above.

28. Pick up the incorrect statement from the following :

A. Iron salts produce heavy flocs and hence remove more suspended matter
B. Iron salts remove hydrogen sulphides
C. Iron salts can be used over a limited range of pH values
D. Iron salts impart corrosiveness to water.

29. The percentage of chlorine in fresh bleaching powder is roughly

A. 50 to 60
B. 30 to 35
C. 40 to 50
D. 20 to 25

30. Higher yield may be expected from

A. gravity springs
B. surface springs
C. artesian springs
D. all the above.

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

A. at the level of water of the source
B. at the bottom of water of the source
C. at about 2.5 m above the bottom
D. none of these.

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

A. 10
B. 15
C. 20
D. 25

33. The maximum permissible hardness for public supplies is

A. 95 mg/litre
B. 105 mg/litre
C. 115 mg/litre
D. 125 mg/litre
E. 150 mg/litre.

34. Plain chlorination is used for water

A. with turbidities less than 20 mg/litre
B. obtained from clear lakes
C. consumed during emergencies
D. supplies to armies during war
E. all the above.

35. Underground water is obtained from

A. rains
B. rivers
C. lakes
D. reservoirs
E. springs.

36. Water may contain

A. bicarbonate alkalinity
B. carbonate alkalinity
C. hydroxide alkalinity
D. caustic alkalinity
E. all the above.

37. Pick up the correct statement from the following :

A. The pH value of neutral water is 7
B. The maximum acidity is obtained when pH value is zero
C. The maximum alkalinity is obtained when pH value is 14.
D. All the above.

38. For controlling algae, the most commonly used chemical, is

A. copper sulphate
B. alum
C. lime
D. bleaching powder.

39. According to Godrich the ratio of peak demand rate to mean demand is

A.
B.
C.
D.
E. All the above.

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

A. maximum depth of water table below ground level
D. frictional losses in the delivery pipe
E. all the above.

41. Rapid sand filter

A. should be preceeded by coagulation and sedimentation
B. uses rapid sand as filter media
C. is used after slow sand filtering has been done
D. can combine disinfection also.

42. Pick up the correct statement from the following :

A. Copper pipes are highly resistant to acidic and alkaline water
B. Wrought iron pipes are lighter than cast iron pipes
C. Wrought iron pipes corrode quickly and are less durable
D. Wrought iron pipes coated with zinc, are called galvanised iron pipes
E. All the above.

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

A. 50%
B. 60%
C. 70%
D. 80%
E. 90%.

44. Cast iron pipes

A. are widely used in city water supplies
B. resist corrosion satisfactorily
C. may last for 100 years
D. are normally manufactured in lengths of about 3.5 m
E. all the above.

45. Run off is the quantity of water which flows

A. in sewer pipes
B. due to leakage in pipes
C. in rivers
D. none of these.

46. Efficiency of removing bacterias from raw water by a slow sand filter, is

A. 80% to 81%
B. 85% to 86%
C. 90% to 97%
D. 98% to 99%.

47. De-chlorination is followed by

A. post-chlorination
B. pre-chlorination
C. double-chlorination
D. super-chlorination.

48. The bed slope in slow sand filters, is generally kept

A. 1 in 50
B. 1 in 75
C. 1 in 100
D. 1 : 200

49. When gravity and pumping systems of water distribution are adopted, the type of distribution reservoir, is

A. elevated tank
B. ground source reservoir
C. intz tank
D. stand pipe.

50. The average domestic consumption under normal conditions in an Indian city per day per person, is

A. 105 litres
B. 115 litres
C. 125 litres
D. 135 litres
E. 150 litres.