11th Chemistry NCERT notes

Viable Particulates:

They are minute living organisms that are dispersed in the atmosphere. (e.g., bacteria, fungi, moulds, algae, etc.)

Non- Viable Particulates

  • Smoke: It is the mixture of solid and liquid particles formed during combustion of organic matter. E.g., Cigarette smoke, smoke from burning of fossil fuel.
  • Dust: Composed of fine solid particles (Over 2 gm in diameter). It is produced during crushing, grinding and attribution of solid particles.
  • Mist: These are produced due to the spray of liquids like herbicides and pesticides over the plants. They travel through air and form mist.
  • Fumes: They are generally released to the atmosphere by the metallurgical operations and also by several chemical reactions.


Smoke is a mixture of smoke, dust particles and small drops of fog.

Smog exists in two types:

  • Classical Smog
  • Photochemical Smog


Formation of Photochemical Smog

Formation of Photochemical Smog

Formation of Photochemical Smog

Harmful effects of photochemical smog:

It can cause cough, bronchitis, irritation of respiratory system etc.

  • To control this type of pollution the engines of the automobiles are fitted with catalytic converters to check the release of both oxides of nitrogen and hydrocarbons in the atmosphere.
  • Some plants like Vitis, Pinus, Juniparus, Quercus, Pyrus can metabolise nitrogen oxide and therefore, their plantation can be done.



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