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CBSE Gujarat Board Haryana Board

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Class 10 Class 12

Which of the following in sewage treatment remove suspended solids?

  • Tertiary treatment

  • Secondary treatment

  • Primary treatment

  • Sludge treatment


Primary treatment

What is the term for the inflammation of cornea due to high absorption of UV-B radiation :
  • myopia
  • snow blindness
  • biomagnification
  • None of the above


snow blindness

Which of the following pollutants is not produced by exhaust of motor vehicles ?
  • CO
  • Hydrocarbon
  • Fly-ash
  • NO



Ozone depletion will cause :
  • Forest fire
  • Pneumonia
  • Increased incidence of skin cancer
  • None of these


Increased incidence of skin cancer

The meaning of BOD is :
  • Bacterial oxygen demand
  • Biological optimum density
  • Biochemical oxygen demand
  • Bioorganisation decay


Biochemical oxygen demand

In the scrubber in the electrostatic precipitator the gases are passed through :
  • filter
  • lime
  • spray of water
  • both 2 and 3


both 2 and 3