Environmental Engineering problems
- 1. Pick out the wrong statement.
Options- A. Biological oxygen demand (BOD) is a characteristic and not a constituent of water.
- B. BOD is a measure of the amount of oxygen which will be demanded & used in 5 days by the biological decomposition of the organic matter present in water stream present as food for the living organism.
- C. BOD is expressed in mg/litre (typically, BOD=2.5 mg/litre for potable water).
- D. none of these Discuss
Correct Answer: none of these
- 2. The weakest sound that can be heard by a person in a quiet environment is equivalent to __________ decibel.
Options- A. 1
- B. 5
- C. 10
- D. 20 Discuss
Correct Answer: 1
- 3. Water filtration rate in a slow sand filter ranges from __________ litres/m2/hr.
Options- A. 10 to 20
- B. 100 to 200
- C. 1500 to 2500
- D. 4000 to 5000 Discuss
Correct Answer: 100 to 200
- 4. Presence of nitrogen in high concentration in contaminated air reduces partial pressure of oxygen in lungs, thereby causing asphyxia (suffocation) leading to death from oxygen deficiency. Concentration of N2 in contaminated air at which it acts as a natural asphyxant is ? __________ percent.
Options- A. 84
- B. 88
- C. 80
- D. 92 Discuss
Correct Answer: 84
- 5. The pH value of potable water should be between
Options- A. 1 to 1.5
- B. 6.5 to 8
- C. 13 to 14
- D. 4 to 5 Discuss
Correct Answer: 6.5 to 8
- 6. Maximum permissible residual chlorine in treated water should be __________ mg/litre.
Options- A. 0.001 to 0.01
- B. 02 to 0.3
- C. 2 to 3
- D. 5 to 10 Discuss
Correct Answer: 02 to 0.3
- 7. Disinfection of water is done to destroy pathogenic bacteria and thus prevent water-borne diseases. Disinfection of water may be done by the use of
Options- A. ozone and iodine.
- B. chlorine or its compounds.
- C. ultraviolet light for irradiation of water.
- D. all (a), (b) & (c). Discuss
Correct Answer: all (a), (b) & (c).
- 8. Inorganic impurities causing water pollution is
Options- A. fats
- B. carbohydrates
- C. salts of metals
- D. protein Discuss
Correct Answer: salts of metals
- 9. TLV of ammonia, nitrogen dioxide and phenol vapor in air is __________ ppm.
Options- A. 5
- B. 100
- C. 1000
- D. 2000 Discuss
Correct Answer: 5
- 10. Noise level inside a jet air liner in normal flight is about __________ decibels.
Options- A. 80
- B. 100
- C. 125
- D. 145 Discuss
Correct Answer: 100
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