2-Methylheptane is a branched-chain alkane and an isomer of octane.
It is an heptane molecule with a methyl group attached to its second atom.
It is a flammable colorless liquid used as fuel.
[2] If the standard definition of the prefix "iso-" is strictly used then 2-methylheptane can be called "Isooctane".
However this name is usually used for another much more important isomer of octane 2,2,4-trimethylpentane.