The pronoun 'who' is used as a subject pronoun.
The pronoun 'whom' is used as an object pronoun.
The pronouns 'who' and 'whom' are interrogative pronouns and relative pronouns.
An interrogative pronoun introduces a question.
A relative pronoun introduces a relative clause.
Examples:
Who is your new math teacher? (interrogative pronoun, subject of the sentence)
Mr. Smith who taught science is also teaching math. (relative pronoun, subject of the relative clause)
To whom should I give my completed application? (interrogative pronoun, object of the preposition 'to')
The manager is the one to whom you give the application. (relative pronoun, object of the preposition 'to')
The correct usage would be "whom you are" in formal writing, as "whom" is the objective form of the pronoun "who." In casual conversation, "who you are" is more commonly used.
The sentence "I ain't hungry" is considered nonstandard usage because it employs a contraction (ain't) that is not typically considered formal or grammatically correct in standard English. This is because "ain't" is a colloquial form that is generally avoided in formal writing.
Whom is properly used whenever the pronoun is the object of a verb or a preposition. The only times many people use the word whom is when they are asking a question about somebody else. For example, " Whom are you refering to?"
formal usage
Are you asking if this expression would be acceptable in formal English? It may not be the worst usage in formal English, but I would look for another way to say it. It is idiomatic, and may not give a consistent meaning to any reading expecting standard usage.
Yes, "whom" can be the object of a preposition (for whom, with whom, of whom, etc.).
formal usage
Our USA grammar originated from England's common usage grammar
To whom it may concern;
To whom it may concern Who is a subject pronoun; it is used as the subject of a verb. Whom is an object pronoun. If you find you can replace who/whom with he, she, or they, who is correct. If you find you've replaced who/whom with him, her, or them, then whom is correct.
Yes, "By whom was this written?" is a correct question. It is the formal and grammatically accurate way to ask about the authorship of a written work.
The word whomever is a pronoun. It is the formal usage of whoever.