Is rare an abstract noun

Answer 1

No, the word 'rarely' is not a noun. The word 'rarely' is an adverb, a word that modifies a verb, an adjective, or another adverb as not often; seldom.
Example: He is rarely late for lunch (modifies the adjective 'late').

A noun is a word for a person, a place or a thing.
An abstract noun is a word for a thing that can't be experienced by any of the five physical senses; it can't be seen, heard, smelled, tasted, or touched.
Example: He rarely speaks of his past. (the adverb 'rarely' modifies the verb 'speaks'; the word 'past' is an abstract noun, a word for a concept)