Question

PAN (peroxyacetyl nitrate) is an important constituent of photochemical smog. It is

• A. Primary pollutant
• B. Secondary pollutant
• C. Natural pollutant
• D. Corollary pollutant

Answer 1

The correct option is B Secondary pollutant

PAN is an important constituent of photochemical smog which are powerful respiratory and eye irritants. These are secondary pollutants, which means they are not emitted directly but they are formed from other pollutants by chemical reactions in the atmosphere. Free radical reactions catalyzed by ultraviolet light from the sun oxidize unburned hydrocarbons to aldehydes, ketones, and dicarbonyl compounds, whose secondary reactions create peroxyacyl radicals, which combine with nitrogen dioxide to form peroxyacyl nitrates.

So, the correct answer is option B.