Question

What is the term used to describe a substance that pollutes the air, water or land?
A. A pollutant
B. Litter
C. A landfill
D. Wastewater

Answer 1

Hint: Pollution is something that causes harm or has some hazardous effect to the environment. Pollution can be natural as well as manmade. Pollution can be on air, water or land. Even unwanted noise is a type of pollution.

Complete Solution :
- The term pollution is derived from the Latin word pollution which has a meaning 'defile or to make dirty. A substance present in the environment in greater population than in natural abundance and resulting in harmful or detrimental effect is called pollutant and this phenomenon is known as pollution. For example, carbon monoxide, sulfur dioxide, ozone and nitrogen dioxide are present in air. In case their percentage increases because of human activities, these are likely to cause pollution.

- In addition to this, there are certain substances which are not at all present in the environment But the release of such substances as a result of the chemical reactions will lead to pollution. These are known as contaminants. For example, methyl isocyanate ($C_2{H}_{3}NCO$) also called MIC released from the Union Carbide Factory at Bhopal contaminated the environment to such a large excess that thousands lost their lives. It is interesting to note that the substances which are normally considered harmless can also cause pollution in case they are present in undesirable concentrations and also at wrong places. For example, nitrates of sodium, potassium and ammonium are added to the soil in order to increase plant growth. But the excess of nitrates present in drinking water are injurious to human beings particularly the children.
So, the correct answer is “Option A”.

Note: Some Natural Sources of pollutants are Volcanic eruptions which results in the release of poisonous gases like $S{O}_2,N{O}_2,H_{2}S,C{O}_2$ etc which are the main sources of pollution. Decay of vegetation, forest fires, pollen grains of flowers are also some sources which lead to pollution.