Water Supply Civil Engineering Questions and Answers - Set 09 - ObjectiveBooks

# Practice Test: Question Set - 09

1. A slow sand filter is cleaned if its filter head is higher than
(A) 10 cm to 20 cm
(B) 20 cm to 40 cm
(C) 40 cm to 70 cm
(D) 70 cm to 120 cm

2. The intake opening is generally covered by a screen to prevent entry of debris etc. and its level is kept
(A) At the level of water of the source
(B) At the bottom of water of the source
(C) At about 2.5 m above the bottom
(D) None of these

3. If four fires break out in a city of population 40 lakhs and if each hydrant has three streams and duration of each fire is four hours, the total quantity of water required, is
(A) 1880 kilo liters
(B) 2880 kilo liters
(C) 3880 kilo liters
(D) 4880 kilo liters

4. Steel pipe are
(A) Suitable for withstanding high internal pressure
(B) Connected by riveted or welded joints
(C) Generally laid underground and no expansion joint is required
(D) Likely to last 100 years under ordinary conditions

5. When gravity and pumping systems of water distribution are adopted, the type of distribution reservoir, is
(A) Elevated tank
(B) Ground source reservoir
(C) Intz tank
(D) Stand pipe

6. The force which develops in a pressure conduit supported on trestles, is
(A) Tension
(B) Compression
(C) Temperature stress
(D) Flexural stress

7. Standard unit of turbidity of water is in one liter of distilled water, one milligram of finely divided
(A) Silica
(B) Mud
(C) Clay
(D) Organic matter

8. For complete stabilisation of organic matter in polluted water, it takes
(A) 5 days
(B) 10 days
(C) 20 days
(D) 30 days

9. If intensity of rainfall in cm per hour is I, percentage coefficient of run-off is P, area of catchment in square kilometers is A, the total run-off Q, is given by
(A) Q = 1.758 × 102 × API
(B) Q = 2.758 × 102 × API
(C) Q = 2.758 × 103 × API
(D) Q = 2.758 × 103 × A/PI

10. The external load per unit length of
(A) A pipe laid on, or projecting above the undisturbed ground and covered with fills, is proportional to the square of the external diameter of the pipe
(B) A flexible pipe buried in narrow trenches and thoroughly compacted side fills, is proportional to the product of the width of the trench and diameter of the pipe
(C) A rigid pipe buried in a narrow trenches and thoroughly compacted side fills, is proportional to the square of the width of the trench
(D) All the above

11. Shales are
(A) Porous
(B) Permeable
(C) Porous and permeable
(D) Porous but not permeable

12. The best process of disinfection of public water supply, is by
(A) Boiling
(B) Chlorination

13. Pick up the correct statement from the following:
(A) Head loss in smaller size pipes at equal velocities, is less
(B) Cost of pumping is less in smaller size pipes
(C) Cost of smaller pipes is comparatively more
(D) None of these

14. 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

15. Surge tanks are used
(A) For storage water
(B) To increase the velocity in a pipeline
(C) As overflow valves
(D) To guard against water hammer

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