Here's why:

* Organic compounds are defined as compounds containing carbon (C) as the primary element, usually bonded with hydrogen (H) and other elements like oxygen (O), nitrogen (N), sulfur (S), phosphorus (P), etc.

* NO2 contains nitrogen (N) and oxygen (O) but lacks carbon (C), which is the defining characteristic of organic compounds.

Therefore, NO2 is considered an inorganic compound.