Concept:2-methylpropane and butane are structural isomers, both with the molecular formula C4H10 and both alkanes.Explanation:1. 2-methylpropane: CH3CH(CH3)CH3 has 4 carbon atoms.2. Butane: CH3CH2CH2CH3 also has 4 carbon atoms.3. Therefore, they have the same number of carbon atoms and belong to the same homologous series.4. Since they are alkanes with the same functional group, they have the same chemical properties.5. Their boiling points differ because 2-methylpropane is branched.Answer:D. They have the same chemical properties