Question

(i) Justify "Dust is pollutant".
(ii) Explain the role of the sun in the formation of the soil.
(iii) Carbon dioxide is necessary for plants. Why do we consider it as pollutant?

Answer 1

(i) Dust remains present in air as suspended particles and can cause allergy and other diseases: It also affects plant growth, by covering stomata on leaf surface. It acts as the carrier of toxic compounds like heavy metals. Thus, we can call dust as pollutant.
(ii) During day time, the rocks get expanded due to the heat of the sun. They contract during night but not at same-rate resulting in cracks in rocks and ultimately resulting into smaller particles and helps in weathering.
(iii) Increasing concentration (more than normal) of $C{O}_2$ is harmful and considered as pollutant. Higher concentrations of $C{O}_2$ is one of the causes of green house effect/global warming. Green-house gases (e.g., $C{O}_2,C{H}_4$ CFCs etc.) are increasing in the atmosphere due to human and natural activities. These gases trap the heat (infra-red radiations) reflected by the earth. This heats up the atmosphere (leads to an increase in earth's temperature). This phenomenon is called global warming which occurs due to green house effect. It may result in melting of polar ice leading to rise in sea level. Coastal regions, thus, will be flooded or might even be submerged.