Answer:
A three-carbon chain has a straight line extending from the center carbon.
Explanation:
Isomers are compounds having the same molecular formula but different structural formulas.
Butane and 2-methylpropane are constitutional isomers. Constitutional isomers differ in the way that the constituent atoms are connected to each other.
Butane is a straight chain compound while the compound 2-methylpropane consists of a three-carbon chain which has a straight line extending from the center carbon.
