The octane rating of gasoline is a measure of the resistance to premature ignition, also known as engine knock. it is based on comparison to a mixture of 2,2,4-trimethylpentane, commonly known as isooctane (rating = 100), and heptane (rating = 0). an octane rating of 90 would compare to a mixture that is 90% isooctane and 10% heptane. isooctane is a highly branched alkane with the condensed structure (ch3)3cch2ch(ch3)2. draw the complete struckture and skeletal struckture.