Answer
In Fig. 4.5, butane and 2-methylpropane in part (b) are structural isomers, as are 1-butene and 2-butene in part (c).
Work Step by Step
To be isomers of one another, molecules must have the same numbers of each kind of atom involved in their structure, which is true for parts (b) and (c) of Fig. 4.5. Structural isomers differ in the covalent arrangement (atoms, bonds) of their parts.
