Which hat is your favorite? What part grammar is the word which in this sentence?
So, when the word "which" is used before a noun (hat), often as an interrogative term (meaning, a word suggesting that there is a question) it is an adjective, describing the noun that follows it. It is no different from saying "The blue hat is my favorite." Instead of using the word "which" as the adjective, you can replace that word with "blue," which is more commonly understood as an adjective. Also, when the word "which" follows a preposition (of) or precedes a verb (is), it is a pronoun. Simply replace the word "which" with a more easily understood pronoun such as "his." Here is an example to illustrate the similarities between the words which and his: Of all the things I own, that blue hat is my favorite, of which I am wearing right now. Of all the people I have known, my boyfriend is my favorite; it is of his charm I am most fond. This word substituting method has helped me develop a better understanding of grammatical concepts.