Quiz: Civil Engineering
Topic: Environmental Engineering

Each question carries 1 mark
Negative marking: 1/4 mark
Time: 10 Minutes

Q1. What does physical characterization of waste water include?
(a) Colour
(b) Odour
(c) Temperature
(d) All of these

Q2. A waste water sample of 2 ml is made up to 300 ml is BOD with distilled water Initial DO of the sample is 8mg/l and after 5 days it is 28mg/l. What is its BOD?
(a) 894 mg/l
(b) 900 mg/l
(c) 300 mg/l
(d) 1200 mg/l

Q3. The two mains gases obtained from anaerobic decomposition are –
(a) Ammonia and CO_2
(b) CO_2 and CH_4
(c) CH_4 and Hydrogen sulphide
(d) Ammonia and CO_4

Q4. The dissolved oxygen in stream is maximum at –
(a) Noon
(b) Morning
(c) Midnight
(d) Same throughout the day

Q5. Unit of deoxygenation constant is
(a) Per day
(b) Per hour
(c) ppm
(d) mg/L

Q6. The correct relationship between theoretical oxygen demand (TOD), biochemical oxygen demand (BOD) and, chemical oxygen demand (COD) is given by

Q7. Facultative bacteria are those which:
(a) Can survive with or without free oxygen
(b) Flourish and thrive in the absence of free oxygen
(c) Require oxygen for their survival
(d) None of the above

Q8. Standard B. O. D. is measured at
(a) 20°C – 1 day
(b) 25°C – 3 day
(c) 20° C – 5 day
(d) 30° C – 5 day

Q9. Which bacteria is used to convert ammonia to Nitrate?
(a) Coliphage
(b) Nitrosomonas
(c) Nitrobacter
(d) E – Coli

Q10. BOD (Bio Chemical Oxygen Demand) of safe drinking water must be:
(a) 0
(b) 50 ppm
(c) 100 ppm
(d) 200 ppm


S1. Ans.(d)
Sol. The physical characteristics of waste water is following.
Suspended solids

S2. Ans.(b)
Sol. Given, volume of diluted sample = 300 ml.
Initial volume of test sample = 2 ml.
Initial dissolved oxygen (DOi)= 8 mg/l
Final dissolved oxygen (DO_F)= 2 mg/l.
▭(BOD=(DOi-DO_F )×Dilution factor)
Dilution factor = (volume of diluted sample)/(Initial volume of test sample)
= 300/2
= 150
BOD= (8-2) ×150
= 900 mg/l.

S3. Ans.(b)
Sol. Gases evolved from anaerobic decomposition are Methane (CH_4) and carbon di-oxide (CO_2).

S4. Ans.(a)
Sol. The dissolved oxygen in stream is maximum at noon.

S5. Ans.(a)
Sol. (i) Deoxygenation constant is given by-
▭(K_(D_(T°_C ) )=K_(D_(20°_c ) ) (1.047)^((T-20) ) ) (Unit→ per day)
K_(D_(T°_c ) )= Deoxygenation constant at temperature T°_C
K_(D_(20°_c ) )= Deoxygenation constant at temperature 20°_C
(ii) Reoxygenation constant is given by
▭(K_(R_(T°_c ) )= K_(R_(20°_c ) ) (1.016)^((T-20) ) )
Where K_(R_(T°_c ) )= Reoxygenation constant at temperature T°_C
K_(R_(20°_c ) )= Reoxygenation constant at temperature 20°_C

S6. Ans.(b)
Sol. The correct relationship between TOD, COD and BOD is-

S7. Ans.(a)
Sol. Facultative bacteria are those who can survive with or without free oxygen.

S8. Ans.(c)
Sol. The amount of oxygen required for the decomposition of bio-degradable organic matter present in the system is referred as bio-chemical oxygen demand (BOD). BOD during 5 days at 20°C is taken as standard BOD.

S9. Ans.(b)
Sol. Nitrosomonas bacteria is used to convert ammonia to nitrate.

S10. Ans.(a)
Sol. Bio-chemical oxygen demand, (BOD) of safe drinking water must be zero.

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