Hello,

You have to read the book to answer these types of questions. This is not your homework Portal.

Anyway here's the answer:

• A primary pollutant is an air pollutant emitted directly from a source. A secondary pollutant is not directly emitted as such, but forms when other pollutants (primary pollutants) react in the atmosphere.

Examples of primary pollutants are particulates, carbon monoxide, nitrogen oxide, and sulfur oxide.

Photochemical smog is made up of various secondary pollutants like ozone, peroxyacyl nitrates (PANs), and nitric acid.

Hope this helps!!!!