43. The drop man holes are generally provided in sewers for

A. industrial areas

B. large town ships

C. hilly town ships

D. cities in plains.

44. With self cleansing velocity in sewers

A. silting occurs at bottom

B. scouring occurs at bottom

C. both silting and scouring occur at bottom

D. neither silting nor scouring occurs at bottom.

45. For efficient working of a sewer, it must be ensured that

A. minimum velocity of 0.45 m/sec, is maintained at its minimum flow

B. a maximum velocity of 0.90 m/sec, is maintained at its maximum flow

C. both A and B

D. neither A nor B.

46. The angle subtended by the surface of sewer water with partial flow, at sewer centre is 120?, the depth of sewerage is

A. 20 cm

B. 25 cm

C. 40 cm

D. 50 cm

47. If the depth of partial flow in a sewer of diameter 2 m, is 50 cm, its wetted perimeter is

A. n

B.n/2

C.n/3

D.2n/3

48. In circular sewers if depth of flow is 0.2 times the full depth, the nominal gradient,

A. is only provided

B. is doubled

C. is trebled

D. is not enough.

49. If the discharge of a sewer running half is 628 1.p.s., = 0.001, and n = 0.010, the diameter of the sewer, is

A. 1.39 m

B. 1.49 m

C. 1.59' m

D.1.69

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