148.  The sewage discharge in a detritus tank of a treatment plant is 576 litres/sec with flow velocity of 0.2 m/sec. If the ratio of width to depth is 2, the depth is
A. 100 cm
B. 110 cm
C. 120 cm
D. 150 cm.

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149.  In primary sedimentation, the 0.2 mm inorganic solids get separated if specific gravity is
A.2.25
B.2.5
C.2.55
D.2.65

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150. The settlement of a particle in sedimentation tank, is affected by
A. velocity of flow
B. viscosity of water
C. size and shape of solid
D. all the above.

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151.  Discrete or granular particles change their
A. size
B. shape
C. weight
D. none of these.

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152.  Flocculated particles do not change their
A. size
B. shape
C. weight
D. none of these.

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153.  The settling velocity of a spherical particle of diameter less than 0.1 mm as per Stock's law, is
A. V, = 418 (G, - G,?)d[100
B. V = 418 (G, - G?.,)d2[ 371070
C. V, = 218 (G, - Gidd2 [ 3T1t107?
D. V, = 218 (G, - Gi?)d[ 3T +

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154.  Hazin's formula= 418 (G, -3T+ 7? is used for the settlement 100 velocity of the particles of diameter
A. less than 0.01 mm
B. less than 0.05 mm
C. less than 0.1 mm
D. greater than 0 1 mm.

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