Question

saturated hydro carbon with blue flame while unsaturated hydrocarbon burn with sooty flame .why?

Answer 1

Unsaturated hydrocarbon,on undergoing combustion, give yellow and sooty flame in the presence of insufficient oxygen because all the unsaturated hydrocarbons contain a large percentage of carbon due to which the amount of oxygen present in the atmosphere is not enough for the complete combustion of carbon Hence , the unsaturated hydrocarbons undergo incomplete combustion and give yellow and sooty flame.

Saturated hydrocarbon , on undergoing combustion give non sooty and blue flame they don't contain so much percentage of carbon as unsaturated carbons contain. Hence they give rise to complete combustion and produce non sooty and blue flame.