5.12 I can recall the problems associated with the frational distillation of crue oil

Read Chem4you P.145
a. when crude oil undergoes fractional distillation there are too many long chain hydrocarbons(eg. bitumen, lubricating oil)and produced not enough short chain hydrocarbons (eg. petrol gas, diesel)

b. To solve these problems, long chain hydrocarbons undergo a chemical reaction called crackling