Final answer:
The underlined carbon atom (CH₃)₂CHCH₂CH₃ is a secondary carbon because it is bonded to two other carbon atoms.
option c is the correct
Step-by-step explanation:
To classify the underlined carbon atom in the molecular structure (CH₃)₂CHCH₂CH₃, we need to determine the number of carbon atoms to which it is directly bonded. In this structure, the underlined carbon atom (₂CH₂) is bonded to two other carbon atoms: one from the CH₃ group and another from the CH₂ group.
Therefore, according to the definitions provided, a carbon atom with two single bonds with other carbon atoms is classified as a secondary carbon. The underlined carbon atom in this molecule is a secondary carbon because it is bonded to two other carbon atoms and not three or four, which would make it tertiary or quaternary, respectively.