21. Biochemical Oxygen Demand (B.O.D.) of safe drinking water must be A. nil B. 5 C. 10 D. 15 Answer & Solution Discuss in Board Save for Later Answer & Solution Answer: Option A No explanation is given for this question Let's Discuss on Board
22. For determining the velocity of flow of underground water, the most commonly used non-empirical formula is A. Darcy’s formula B. Slichter’s formula C. Hazen’s formula D. Lacy’s formula Answer & Solution Discuss in Board Save for Later Answer & Solution Answer: Option A No explanation is given for this question Let's Discuss on Board
23. Aeration of water is done to remove A. odour B. colour C. bacterias D. hardness Answer & Solution Discuss in Board Save for Later Answer & Solution Answer: Option A No explanation is given for this question Let's Discuss on Board
24. Disinfection of drinking water, is done to remove A. odour B. bacterias C. turbidity D. colour Answer & Solution Discuss in Board Save for Later Answer & Solution Answer: Option B No explanation is given for this question Let's Discuss on Board
25. Specific capacity or yield of wells, is generally expressed, as A. m3/sec B. m3/hour C. m3/hour/m2 D. m3/hour/m2/m Answer & Solution Discuss in Board Save for Later Answer & Solution Answer: Option D No explanation is given for this question Let's Discuss on Board
26. The least thickness of class B cast iron (spun) pipe, is A. 7.2 mm B. 7.9 mm C. 8.6 mm D. 10 mm Answer & Solution Discuss in Board Save for Later Answer & Solution Answer: Option C No explanation is given for this question Let's Discuss on Board
27. The maximum depth of sedimentation tanks is limited to A. 3 m B. 4 m C. 5 m D. 6 m Answer & Solution Discuss in Board Save for Later Answer & Solution Answer: Option D No explanation is given for this question Let's Discuss on Board
28. Corrosion of well pipes may not be reduced by A. reducing the draw down and the pumping rate B. reducing the flow velocity C. using thicker pipes D. using screens having larger area of openings Answer & Solution Discuss in Board Save for Later Answer & Solution Answer: Option D No explanation is given for this question Let's Discuss on Board
29. Pick up the incorrect statement from the following. The underground sources of water, is from A. wells B. springs C. infiltration wells D. storage reservoirs Answer & Solution Discuss in Board Save for Later Answer & Solution Answer: Option D No explanation is given for this question Let's Discuss on Board
30. Pick up the correct statement from the following: A. The water level in a still well, represents the ground water table level B. The difference between water table level and the water level in a well after pumping, is called depression head C. The surface of water table surrounding a well during pumping, forms a cone of depression D. All the above Answer & Solution Discuss in Board Save for Later Answer & Solution Answer: Option D No explanation is given for this question Let's Discuss on Board