n-Pentane is a chain-like hydrocarbon from the alkane group with the chemical formula C₅H₁₂. It is the unbranched representative of the Pentane isomers.

n-Heptane is a chain-like hydrocarbon from the alkane group with the chemical formula C₇H₁₆. It is the unbranched representative and technically the most important of the nine heptane isomers.

iso-Octane is a branched hydrocarbon from the alkane group with the chemical formula C8H18. It is the most important of the eighteen octane isomers. Since it is an important component of motor gasoline, it is produced synthetically, but is also found to a small extent in petroleum.

n-Octane is a chain-like hydrocarbon from the alkane group with the chemical formula C₈H₁₈. It is the unbranched representative and of the eighteen octane isomers.