Final answer:
The functional group present in aspirin but not in ethyl salicylate is the carboxylic acid group. Aspirin includes an ester and a carboxylic acid group; ethyl salicylate only has an ester group.
Step-by-step explanation:
The functional group present in aspirin but not in ethyl salicylate is a carboxylic acid group. Aspirin, or acetylsalicylic acid, contains both an ester group and a carboxylic acid group. Ethyl salicylate, on the other hand, only has an ester group and does not contain any carboxylic acid group. Therefore, the correct answer to which functional group is present in aspirin but not in ethyl salicylate is the carboxylic acid group.