Chlorine atoms in the upper atmosphere cause the breakdown of ozone.
Cl+O3→O2+ClO
ClO+O→Cl+O2
Which statements about these chlorine atoms are correct?
1. The chlorine atoms act as catalysts.
2. The chlorine atoms are free radicals.
3. The chlorine atoms are formed by heterolytic fission of a covalent bond in chlorofluorocarbons.