Recently my students just carried out experiments to compare hexane(C6H14) and (C6H14) in terms of sootiness of flame during combustion. Filter papers are used to collect soot formed during the experiments.
It is obvious from the filter papers, hex-1-ene produces more soot than hexane during combustion. It is due to percentage of carbon content. Though both hex-1-ene and hexane have 6 carbon atoms per molecule, but hex-1-ene has higher percentage of carbon content than hexane.