Alkanes:
Alkanes of a specific molecular formula can present as different constitutional isomers. For instance, the alkane that comprising the molecular formula C4H10 can available as two constitutional isomers that is:
1. The straight chain alkane (butane) or
2. The branched alkane (2-methylpropane).
These are dissimilar compounds with diverse physical and chemical properties.
Figure: (a) Butane (C4H10); (b) 2-methylpropane (C4H10).