Chapter => 18 (Pollution of Air & Water) of Class 8 Definitions

These are definitions of Chapter => 18 (Pollution of Air & Water) of Class 8, Learn and Practice For CBSE Examinations.

1.   Pollution =>The presence in or introduction into the environment of a substance which has harmful or poisonous effects.

2.   Air Pollution =>When air is contaminated by unwanted substances which has a harmful effect on both the living and the non-living, is referred to as air pollution.

3.   Water Pollution =>Water pollution is the contamination of water bodies (e.g. lakes, rivers, oceans, aquifers and groundwater). This form of environmental degradation occurs when pollutants are directly or indirectly discharged into water bodies without adequate treatment to remove harmful compounds.

4.   Pollutants  =>A substance that pollutes something, especially water or the atmosphere.

5.   Air Pollutants =>The substance which contaminate with air are called air pollutants.

6.   Water Pollutants =>Whenever harmful substances such as sewage, toxic chemicals, silt, etc., get mixed with water, the water becomes polluted .The substance that pollute water is called water pollutants.

7. Smog =>A thick fog-like layer in the atmosphere, especially in winters is called smog .Which is made up of fog and smoke .Smog causes breathing difficulties such as asthma, cough ad wheezing in children  .Smoke combine with other air pollutants and fog to form smog.

8. Smoke =>Smoke may contain oxides of nitrogen which combine with other air pollutants and fog to form smog.

9. Sulphur Dioxide =>It is produced by combustion of fuels like coal in power plants .It can cause respiratory problems, including permanent lung damage.

10. Power Plants =>An engine or other apparatus which provides power for a             machine, building, etc.

11. Green House Effect => The greenhouse effect is the process by which radiation       from a planet's atmosphere warms the planet's surface to a temperature above       what it would be without its atmosphere.

12. Global Warming => A gradual increase in the overall temperature of the earth's   atmosphere generally attributed to the greenhouse effect caused by increased         levels of carbon dioxide, CFCs, and other pollutants.

13. Ganga Action Plan =>An ambitious plan to save the river , called the Ganga            action plan was launched in 1985 .It aimed to reduce the pollution level in the        river.

  14.  Green House Gases => A gas that contributes to the greenhouse effect by                      absorbing infrared radiation. Carbon dioxide and chlorofluorocarbons are                    examples of greenhouse gases.

15. Potable Water =>Water which is suitable for drinking is called potable water.

16. Boiling =>Many household use boiling as a method for obtaining safe drinking water .Boiling kills the germs present in the water.

17. Chlorination =>It is a commonly used chemical method for purifying water .It        is done by adding chorine tablets or bleaching powder to the water .We must be    cautions .We should not use more chlorine tablets than specified.

18. Chemical Contamination =>Chemical contaminants are chemicals toxic to plants   and animals in waterways. The phrase 'chemical contamination' is used to          indicate situations where chemicals are either present where they shouldn't be, or   are at higher concentrations than they would naturally have occurred.