Multiple choice Which of the following compounds measures the cetane number? Cyclopentadienyl manganese carbonyl n-hexadecane Tetraethyl lead Iso-octane (3) and (4) are correct Reveal answer Fill a bubble to check yourself B Correct answer Explanation This option is correct because the cetane number is used for the measuring of the knocking character of the fuels in diesel engines and ignites very readily, hence this measures the cetane number.