Question

1. define ozone and explain its purpose.

Explanation:

Ozone ($O_3$) is a gas composed of three oxygen atoms. In the stratosphere, the ozone layer absorbs most of the Sun's harmful ultraviolet (UV) radiation, protecting life on Earth from excessive UV exposure which can cause skin cancer, cataracts, and harm ecosystems. At ground level, ozone (a pollutant in smog) is formed from pollutants reacting in sunlight and can irritate respiratory systems, but stratospheric ozone is vital for protection.

Answer:

Ozone is a triatomic molecule ($O_3$) of oxygen. Stratospheric ozone forms a layer that absorbs harmful UV radiation, protecting life; ground - level ozone (pollutant) is a by - product of pollution reactions, with negative health/ecosystem impacts.