Question

how photochemical reaction is responsible for destroying a protective layer in
the atmosphere

Answer 1

Photochemical reaction, a chemical reaction initiated by the absorption of energy in the form of light. The consequence of molecules’ absorbing light is the creation of transient excited states whose chemical and physical properties differ greatly from the original molecules. These new chemical species can fall apart, change to new structures, combine with each other or other molecules, or transfer electrons, hydrogen atoms, protons, or their electronic excitation energy to other molecules. Excited states are stronger acids and stronger reductants than the original ground states.