A. separate system
B. combined system
C. partially separate system
D. partially combined system
✅ The correct answer is option B.
Environmental Engineering MCQs
32. Ground water is usually free from________________?
A. suspended impurities
B. dissolved impurities
C. both suspended and dissolved impuri¬ties
D. none of the above
✅ The correct answer is option A.
33. For satisfactory working of a sludge digestion unit, the pH range of digested sludge should be maintained as___________________?
A. 4.5 to 6.0
B. 6.5 to 8.0
C. 8.5 to 10.0
D. 10.5 to 12.0
✅ The correct answer is option B.
34. The type of valve which allows water to flow in one direction but prevents its flow in the reverse direction is____________________?
A. reflux valve
B. sluice valve
C. air relief valve
D. pressure relief valve
✅ The correct answer is option A.
35. The self cleansing velocity for all sewers in India is usually_________________?
A. less than 1.0 m/sec
B. 1.0 m/sec to 1.2 m/sec
C. 1.5 m/sec to 2.0 m/sec
D. 3.0 m/sec to 3.5 m/sec
✅ The correct answer is option B.
36. Corrosion in concrete sewers is caused by______________?
A. septic conditions
B. dissolved oxygen
C. chlorine
D. nitrogen
✅ The correct answer is option A.
37. The minimum dissolved oxygen which should always be present in water in order to save the aquatic life is______________?
A. 1 ppm
B. 4 ppm
C. 10 ppm
D. 40 ppm
✅ The correct answer is option B.
38. Select the correct relationship between porosity (N), specific yield (y) and specific retention (R)________________?
A. N = y + R
B. y = N + R
C. R = N + y
D. R > (N + y)
✅ The correct answer is option A.
39. The minimum and maximum diameters of sewers shall preferably be_________________?
A. 15 cm and 100 cm
B. 15 cm and 300 cm
C. 30 cm and 450 cm
D. 60 cm and 300cm
✅ The correct answer is option B.
40. Disinfection efficiency is________________?
A. reduced at higher pH value of water
B. unaffected by pH value of water
C. increased at higher pH value of water
D. highest at pH value equal to 7
✅ The correct answer is option A.