Here's why:
* Abstract nouns refer to concepts, ideas, qualities, or feelings that cannot be touched. Examples include love, happiness, justice, and freedom.
* "Tour" refers to a concrete activity or event. It involves physical movement and is something you can participate in.
Here's how to think about it:
* You can't touch or hold "love" or "justice."
* You can, however, experience a "tour" and be physically present during it.
Therefore, "tour" is a concrete noun, specifically a common noun.