PAN stands forA. Per acetyl nitrateB. PeroxyacetylC. Peroxyacetyl nitrateD. Pyridine acetonitrile

The correct answer is C. Peroxyacetyl nitrate.

Here's the detailed explanation:

PAN stands for Peroxyacetyl Nitrate. It is a chemical compound that is formed by the reaction of acyl peroxides with nitrogen oxides (NOx). PAN is commonly found in photochemical smog and is a significant atmospheric pollutant. It is formed when ozone reacts with volatile organic compounds (VOCs), and the compound can be harmful to human health and the environment.

The other options are incorrect:

A. Per acetyl nitrate: This is not a correct term or compound.
B. Peroxyacetyl: This is part of the name of PAN, but it is not a full compound name.
D. Pyridine acetonitrile: This is a different compound entirely and unrelated to PAN.
Thus, the full name of PAN is Peroxyacetyl Nitrate.