Noun
n-pentane (uncountable)
(organic chemistry) The saturated aliphatic hydrocarbon (CH3(CH2)3CH3).
In the table below, the hydroxyl group can occupy three different positions on an n-pentane chain forming three different compounds. Source: Internet
Pentane exists as three isomers: n-pentane (often called simply "pentane"), isopentane (2-methylbutane) and neopentane (dimethylpropane). Source: Internet