Detailed Instructions: You are given a passage. You need to construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) its answer is the whole paragraph. Avoid creating questions that can be answered correctly without actually understanding the paragraph.
Problem:The main products still are carbon dioxide and water, together with carbon monoxide and various substances collectively referred to as soot. Soot basically is the attempt to form graphitic carbon in the flame finished before a sufficient quantity has formed to create crystals. Substances in soot usually are polycyclical aromatic compounds, or heterocyclical compounds like furanes.

In the case of impure fuels, additional side products can be found. Presence of halogens leads to formation of dioxines and similar compounds. Presence of sulfur leads to all kind of noxious substances. Etc.

Incomplete combustion doesn't provide well-defined reactions.
Solution:
what are the main products of the incomplete combustion of fossil fuels?