Remy is smoking too closely to a building that manufactures fertilizer. when he puts out his cigarette near the hazardous waste, it sparks a fire because the fertilizer is flammable. what kind of hazard did the chemical waste cause?

 class 4 hazard, flamable solids.

Explanation: The flammable waste is known as a flammable hazard, and depending on the velocity that it turns into fire, it also can be an explosive hazard. In this case, we know that it "sparks" fire (which may talk about this don't being spontaneous), so this may only be treated as a class 4 hazard, flammable solids or substances, of subclass 4.1 "flamable solids".  

Something that you may take in mind when talking about this thing is that the classification may change from country to country or over the time (as more information and new regulations come out) so it is recommended to stay actualized with this.