emmm... I feel a bit daft asking this as an English speaker,but are day, smell and air abstract or concrete nouns? My friends and I are having a bit of a bet, it would be good to hear an official answer! Thank you!
By that definition (and there may be better ones), the 24-hour day is an abstraction. However, day as the noun meaning the period of light between dawn and dusk, is certainly perceivable.
A smell is perceivable; the sense of smell is not.
Air is not perceivable if it is clean and not moving. However, it is composed of nitrogen, oxygen, water vapor, casrbon dioxide. It is difficult to consider something composed of matter to be an abstraction.
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