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  • Question

  • 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

  • Correct Answer
  • none of these 

    • Environmental Engineering problems

    Search Results

    • 1. Water filtration rate in a rapid sand filter ranges from __________ kilolitres/m2/hr.

    • Options
    • A. 0.1 to 1
    • B. 3 to 6
    • C. 10 to 15
    • D. 15 to 20
      • Discuss
    • 2. Fluorosis is caused due to the presence of excessive amount of __________ in drinking water.

    • Options
    • A. mercury
    • B. lead
    • C. fluoride
    • D. arsenic
      • Discuss
    • 3. Photochemical smog is formed from automobile exhaust

    • Options
    • A. by reaction of hydrocarbon & nitric oxide in presence of sunlight.
    • B. appears only on sunny days.
    • C. is harmful for crops and trees also besides causing eye irritation & asthma.
    • D. all (a), (b) & (c)
      • Discuss
    • 4. Threshold limit value (TLV) means maximum permissible/acceptable concentration. TLV of phosgene in air is about __________ ppm (parts per million).

    • Options
    • A. 0.002
    • B. 0.2
    • C. 1.2
    • D. 4.8
      • Discuss
    • 5. Disinfection of water is done to remove

    • Options
    • A. color
    • B. bad taste
    • C. foul odour
    • D. bacteria
      • Discuss
    • 6. 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
    • 7. 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
    • 8. 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
    • 9. 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
    • 10. 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

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