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Class 10 Class 12

According to central pollution control Board (CPCB), which particulate size in diameter (n micrometres) of the air pollutants is responsible for greatest harm to human health?

  • 2.5 or less

  • 1.5 or less

  • 1.0 or less 

  • 5.2 or 2.5 


A.

2.5 or less

Particles in the size range 1-10 μm have measurable settling velocities but are readily stirred by air movements whereas particles of size 0.1-1 μm, a submicroscopic size found in Urban air, undergo random Brownian motion reulting from collisions among individual molecules. Of all the different types of particulates in the atmosphere, the presence of trace elements such as cadmium, lead nickel and mercury may constitute the greatest health hazard.

Particles in the size range 1-10 μm have measurable settling velocities but are readily stirred by air movements whereas particles of size 0.1-1 μm, a submicroscopic size found in Urban air, undergo random Brownian motion reulting from collisions among individual molecules. Of all the different types of particulates in the atmosphere, the presence of trace elements such as cadmium, lead nickel and mercury may constitute the greatest health hazard.

317 Views

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
997 Views

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

C.

Biochemical oxygen demand
687 Views

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

C.

Increased incidence of skin cancer
560 Views

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
695 Views

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

C.

Fly-ash
711 Views