Ozone is composed of trioxygen which is highly reactive gas compared to dioxygen. Ozone layer is present in stratosphere and troposphere and protect the humans from ultraviolet radiations but it may be toxic if inhaled. Ozone can be broken down into molecular oxygen by chlorine and bromine atoms.
A hole was discovered in ozone layer in 1982 and scientist believed that it could be dangerous for human health. The compounds involved in depletion of ozone are mainly Chlorofluorocarbons (CFS) and (HFCS). Then a global agreement was signed in 1987 which leads to prohibition of use of all chemicals that are involved in depletion of ozone layer. The problem of ozone depletion is solved by the agreement and ozone hole started to recover it from 2000.
But recent reports showed that the alternative chemicals used to protect the depletion of ozone layer began to trap the heat inside the earth like greenhouse effect. Now scientists are in search of chemical that can prevent both ozone depletion as well as global warming.
Hey there! The answer is B, Pangaea. This was the name for the large continent that supposedly existed before we had all of our separate continents today (all of which were part of Pangaea). Hope this helps
