11. 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
✅ The correct answer is option C.
Water Supply Engineering MCQs
12. By boiling water, hardness can be removed if it is due to_________________?
A. calcium sulphate
B. magnesium sulphate
C. calcium nitrate
D. calcium bicarbonate
✅ The correct answer is option D.
13. The R.L. of ground water table on the sides of a valley is 1505 m whereas R.L. of the stream water is 1475 m. If 60° slope consists of pervious soil between R.L. 1485 m to 1500 m, the gravity spring may be expected at the point of reduced level_______________?
A. 1500 m
B. 1505 m
C. 1475 m
D. 1485 m
✅ The correct answer is option D.
14. Time of concentration________________?
A. is the time taken, for precipitation
B. duration of rainfall.
C. time taken for all the ran off to reach the drain
D. time taken for the storm water to travel from the most remote point to the drain
✅ The correct answer is option D.
15. 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
✅ The correct answer is option D.
16. The specific retention is least in case of_______________?
A. Clay
B. Sand
C. Silt
D. Coarse gravel
✅ The correct answer is option D.
17. According to IS : 1172-1963, a minimum of 135 litres of water capita per day, is required for________________?
A. Boarding schools
B. Nurses home and medical quarters
C. hostels
D. all the above
✅ The correct answer is option D.