If the flame of a miner’s safety lamp in the upper layers of the sewer forms an explosive, the sewer certainly contains_______________?
		A. Hydrogen sulphide
B. Carbon dioxide
C. Methane
D. Oxygen
		A. Hydrogen sulphide
B. Carbon dioxide
C. Methane
D. Oxygen
		A. Alum
B. Ferric chloride
C. Ferric sulphate
D. Chlorinated copperas
		A. Centrifugal pump
B. Pneumatic ejector
C. Reciprocating pump
D. None of these
		A. 15 days
B. 30 days
C. 60 days
D. 90 days 
		A. Less than 150
B. Between 150 to 200
C. Between 200 to 300
D. More than 500
		A. The sewage when running full from inside, is called internal pressure
B. The internal pressure if any, causes tensile stress in the pipe material
C. Pressure sewers are designed to be safe in tension
D. All the above
		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.
		A. Width of the tank is normally kept about 6 m
B. Length of the tank is normally kept 4 to 5 times the width
C. Maximum horizontal flow velocity is limited to 0.3 m/minute
D. All the above
		A. Water test
B. Smoke test
C. Straightness test
D. All the above
		A. 15 cm c/c
B. 22.5 cm c/c
C. 30 cm c/c
D. 50 cm c/c