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our environment — Science STD 10 — Question

Gujarat BoardEnglish MediumSTD 10Scienceour environment4 Marks
Question
Discuss the formation of Ozone layer.
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Answer

→ Ozone $\left(O_3\right)$ is a molecule formed by three atoms of oxygen. While Oxygen $\left( O _2\right)$ is essential for all aerobic forms of life, Ozone is a deadly poison ous, However, at the higher levels of the atmosphere, Ozone performs an essential function. It shields the surface of the earth from ultraviolet (uv) radiation. from the sun. This radiation is highly damaging to organisms. For example., it causes skin cancer in human beings.
→ Ozone at the higher levels of the atmosphere is a product of $( UV )$ radiation acting on oxygen $\left( O _2\right)$ molecule. The higher energy UV radiations split apart some molecular. Oxygen $\left( O _2\right)$ into free oxygen $(O)$ atoms.
→ These free oxygen atoms then combine with the molecular oxygen to form ozone as shown in the following reaction.
(1) $O _2 \xrightarrow{ UV } O + O$
(2) $O + O _2 \rightarrow O _3$ (Ozone)
→ The amount of ozone in the atmosphere began to drop sharply in the $1980 s$. This decrease has been linked to synthetic chemicals like chlorofluorocarbons (CFCs). Which are used as refrigerants and in fire extinguishers. In 1987, the United Nations Environment Programme (UNEP) succeeded in forging an agreement to freeze CFC production at 1986 levels

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