71.  Stone ware pipes are
A. highly resistant to sulphide corrosion
B. highly impervious
C. hydraulically efficient because of their smooth interior surface
D. specially suited to pressure pipes

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72. The sewer which resists sulphide corrosion, is
A. Brick sewer
B. Cast iron sewer
C. R.C.C. sewer
D. Lead sewer

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73.  For laying a sewer line in a trench of 2 m width, an offset line is marked on the ground parallel to the given centre line at a distance of
A. 100 cm
B. 120 cm
C. 140 cm
D. 160 cm

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74. The reduced levels of the string at the consecutive sight rails A and B are 203.575 m, 203.475 m respectively. If the difference of their R.D.s is 10 m, the gradient of the sewer line is
A. 1 in 100 upward
B. 1 in 500 upward
C. 1 in 100 downward
D. 1 in 503 upward.

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75.  In case of sewer lines
A. water test is carried out to check water tightness of the joints
B. test for straightness is carried out with the help of a lamp and mirror
C. obstruction test is carried out with the help of smooth ball of diameter 13 mm
D. all the above.

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76.  A manhole is generally provided at each
A. bend
B. junction
C. change of gradient
D. all the above.

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77.  The spacing of man holes along a straight portion of a sewer is 300 m, the diameter of the sewer may be
A. 0.9 cm
B. 1.2 m
C. 1.5 m
D. > 1.5 m.

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