For a compound with the molecular formula C5H12, there are three possible chain isomers:1. n-Pentane: a straight chain of five carbon atoms2. Isopentane 2-methylbutane : a four-carbon chain with a methyl group attached to the second carbon3. Neopentane 2,2-dimethylpropane : a three-carbon chain with two methyl groups attached to the second carbonSo, there are 3 possible chain isomers for C5H12.