The compound that is a
structural isomer of butane is 2 – methylpropane. Note that butane has four
carbon atoms. In 2 – methylpropane, propane has three carbon atoms and methyl
is attached at the second carbon. Methyl has only one carbon atom and together,
they have a total of four carbon atoms. An isomer is a substance that has the
same number of atoms but they differ in their structure. The answer is letter
C.
