Civil Engineering - Water Supply Engineering

31. 

The maximum permissible colour for domestic supplies based on cobalt scale, is

A. 5 ppm
B. 10 ppm
C. 15 ppm
D. 20 ppm
E. 25 ppm.

Answer: Option D

Explanation:

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32. 

The dilution ratio at which the odour is hardly detectable is generally called threshold odour number and for public supplies it should not exceed

A. 3
B. 5
C. 7
D. 9
E. 10

Answer: Option A

Explanation:

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33. 

The joint used for joining the plain ends of cast iron pipes, is

A. flanged joint
B. socket and spigot joint .
C. dresser coupling joint
D. flexible joint
E. expansion joint.

Answer: Option C

Explanation:

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34. 

The bacterias which may survive with or without free oxygen, are called

A. Aerobic bacterias
B. Anaerobic bacterias
C. Faculative bacteria's
D. None of these.

Answer: Option C

Explanation:

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35. 

Detention time for plain sedimentation tank usually ranges from

A. 2 to 4 hours
B. 4 to 8 hours
C. 6 to 10 hours
D. 8 to 12 hours
E. 12 to 16 hours.

Answer: Option B

Explanation:

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