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  • Question
  • Threshold Limit Value (TLV) is the maximum allowable concentration (i.e. safe limit) of pollutants in air. Safe limit for SO2 in air is __________ ppm.


  • Options
  • A. 5
  • B. 500
  • C. 1000
  • D. 2000

  • Correct Answer



  • Environmental Engineering problems


    Search Results


    • 1. Fluorosis (a bone disease) is caused by the presence of high concentration of __________ in atmospheric air.

    • Options
    • A. hydrocarbons
    • B. hydrogen flouride
    • C. hydrogen sulphides
    • D. nitrogen dioxide
    • Discuss
    • 2. The main pollutant in waste water discharged from a petroleum refinery is oil (both in free and emulsified form). Free oil is removed by

    • Options
    • A. biological oxygen pond.
    • B. aerated lagoons.
    • C. trickling filters.
    • D. gravity separator having oil skimming devices.
    • Discuss
    • 3. Ionisation potential employed in the industrial electrostatic precipitator is of the order of

    • Options
    • A. 30 to 70 kV DC
    • B. 30 to 70 kV AC
    • C. 230 V AC
    • D. 230 V DC
    • Discuss
    • 4. Aerodynamic noise resulting from turbulent gas flow is the most prevalent source of valve noise in fluid ilow control. It is caused due to

    • Options
    • A. Reynold stresses
    • B. shear forces
    • C. both (a) & (b)
    • D. neither (a) nor (b)
    • Discuss
    • 5. TLV of ozone (O3) and phosgene (COCl2) in air is __________ ppm.

    • Options
    • A. 0.1
    • B. 25
    • C. 100
    • D. 1000
    • Discuss
    • 6. Maximum allowable concentration of CO2 in air for safe working is __________ ppm (parts per million).

    • Options
    • A. 50
    • B. 1000
    • C. 2000
    • D. 5000
    • Discuss
    • 7. Inhalation of lead compounds present in the automobile exhausts (using leaded petrol) causes

    • Options
    • A. blood poisoning.
    • B. anaemia.
    • C. nervous system disorder.
    • D. all (a), (b) and (c).
    • Discuss
    • 8. Operating principle of cyclone separator is based on the action of __________ dust particles.

    • Options
    • A. diffusion of
    • B. centrifugal force on
    • C. gravitational force on
    • D. electrostatic force on
    • Discuss
    • 9. Coal washing waste water containing about 3% suspended solids (comprising of clay, slate, stone etc.) is treated for solid particles removal

    • Options
    • A. by chemical coagulation.
    • B. in sedimentation tanks equipped with mechanical scrapper.
    • C. in vacuum filter.
    • D. in clarifiers.
    • Discuss
    • 10. The ratio of oxygen available to the oxygen required for stabilisation of sewage is called the

    • Options
    • A. bacterial stability factor.
    • B. relative stability.
    • C. biological oxygen demand (BOD).
    • D. oxygen ion concentration.
    • Discuss


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