Isomerism is defined as the existence of compounds that have the same molecular formula but different structural formulas.
According to the question, we are to illustrate the isomers of but-1-ene that show different forms of isomerization. But-1-ene is known to have C₄H₈ six different isomers. The structural formula of these isomers are illustrated below:
The other two are expressed as:
The structural formula of the but-1-ene itself is as illustrated below;