Question Detail

CHM 102 Practice Questions Objective Question

Question

Which hydrocarbon molecule with eight carbons would produce the lowest octane number (i.e., the most knocking) when used as a fuel in automobile?
Options
A 2-Methyl-3,3-dimethylpentane
B n-Octane
Correct Answer
C 2-Isopropylpentane
D 2-Methylheptane
Correct Answer

Option B is the correct answer.

Detailed Explanation

n-Octane (straight-chain alkane) has the lowest octane number among C8 isomers because straight-chain alkanes knock the most. Branched alkanes have higher octane numbers.

Hint

Which type of alkane has the lowest octane number?

Question Info