I want to know if Air is an abstract noun. If yes I want to know Five reasons but if no, I also want to know five reasons
You can see it and hear it when the wind's blowing (wind is moving air), you can feel it; and sometimes you can smell it and taste it (although that's usually something in the air). You can analyze it into nitrogen and oxygen plus a few trace elements.
Why do you think there are five reasons either away? There's really only one. It's a concrete noun because it refers to a tangible physical object.
That's assuming you mean "air" in its primary meaning. If you say "He has an air of superiority", that use is abstract.
I think the author of this thread alludes to I.Kant by his asking to give 5 reasons.