Here's why:
* Concrete nouns refer to things that can be perceived by the senses (sight, touch, smell, taste, hearing). Perfume can be smelled, so it is a concrete noun.
* Abstract nouns refer to concepts, ideas, feelings, or qualities that cannot be touched. While the *idea* of fragrance might be abstract, perfume itself is a physical substance.
Let me know if you have any other word classifications you'd like to explore!