71. A coarse-grained soil has a voids ratio 0.75, and specific gravity as 2.75. The critical gradient at which quick sand condition occurs, is
A.0.25
B.0.5
C.0.75
D. 1.00.

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72.  A critical hydraulic gradient may occur when
A. flow is in upward direction
B. seepage pressure is in upward direction
C. effective pressure is zero
D. all the above.

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73. Darcy's law is applicable to seepage if a soil is
A. homogeneous
B. isotropic
C. incompressible
D. all the above.

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74. During seepage through a soil, direction of seepage is always
A. parallel to equipotential lines
B. perpendicular to stream lines
C. perpendicular to equipotential lines
D. none of these.

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75.  If there is no impervious boundary at the bottom of a hydraulic structure, stream lines tend to follow :
A. a straight line
B. a parabola
C. a semi-ellipse
D. a semi-circle.

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76. The quantity of seepage of water through soils is proportional to
A. coefficient of permeability of soil
B. total head loss through the soil
C. neither A nor (b)
D. both (a) and (b).

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77. The seepage force in a soil, is
A. perpendicular to the equipotential lines
B. proportional to the exit gradient
C. proportional to the head loss
D. all the above.

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