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Biology

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CBSE Gujarat Board Haryana Board

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Class 10 Class 12

Select the correct statement from the following

  • Bio-gas is produced by the activity of aerobic bacteria on animal waste

  • Methanobacterium is an aerobic bacterium found in rumen of cattle

  • Biogas, commonly called gobar gas, is pure methane

  • Activated sludge-sediment in settlement tanks of sewage treatment plant is a right source of aerobic bacteria


C.

Biogas, commonly called gobar gas, is pure methane

Activated sludge is a process dealing with the treatment of sewage and industrial waste waters. Atmospheric air on pure oxygen is introduced to a mixture of primary treated or screened sewage (or industrial waster water) combined with organisms to develop a biological flock, which reduces the organic content of the sewage. Sediment is settlement tanks of sewage treatment plant is a rich source of aerobic bacteria because small amounts are used as inoculum in secondary treatment of biological treatment stage of sewage treatment.

Activated sludge is a process dealing with the treatment of sewage and industrial waste waters. Atmospheric air on pure oxygen is introduced to a mixture of primary treated or screened sewage (or industrial waster water) combined with organisms to develop a biological flock, which reduces the organic content of the sewage. Sediment is settlement tanks of sewage treatment plant is a rich source of aerobic bacteria because small amounts are used as inoculum in secondary treatment of biological treatment stage of sewage 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

B.

snow blindness

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

C.

Fly-ash

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

D.

both 2 and 3

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

C.

Increased incidence of skin cancer

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

C.

Biochemical oxygen demand