Final answer:
Among the compounds listed, only CH₃CHOHCH₃ (isopropyl alcohol or 2-propanol) is a secondary alcohol because the OH group is attached to a carbon that is connected to two other carbon atoms.
Step-by-step explanation:
The secondary alcohols are those where the carbon atom with the hydroxyl (OH) group is attached to two other carbon atoms. The compounds listed in the question can be classified based on this criterion:
- CH₃CH₂OH (ethyl alcohol or ethanol): The OH group is attached to a carbon that is connected to only one other carbon atom, classifying it as a primary alcohol, not a secondary alcohol.
- CH₃CHOHCH₃ (isopropyl alcohol or 2-propanol): Here the OH group is on a carbon atom that is connected to two other carbon atoms, making it a secondary alcohol.
- CH₃OH (methyl alcohol or methanol): The OH group is attached to a carbon that is not connected to any other carbon atoms which is a primary alcohol and the simplest alcohol.
- CH₃CH₂CH₂OH (1-propanol): Similarly to ethanol, this OH group is attached to a carbon that is connected to only one other carbon atom, so this is also a primary alcohol.
Thus, the only secondary alcohol in the given list is CH₃CHOHCH₃ or isopropyl alcohol.