What type of bond belongs in box (3) in figure 3?

Carbon Dioxide is a Covalent Bond

When something is flammable, it burns and burning is a chemical property since the compounds are being broken down and gas is released. If something is non-falammable, it would then be a chemical property as well since the chemical makeup would not be broken by a flame. (I apologize if my answer is a bit broad or unspecific)