1. (Who***, Whom)was the first president of
the United States?
Yes, "who" is correct. It's the subject of the verb.
To determine whether to use "who" or "whom" in this sentence, you need to understand the difference between the two.
1. "Who" is used when the person is the subject of the sentence or clause.
Example: Who was the first president of the United States?
2. "Whom" is used when the person is the object of a verb or preposition.
Example: To whom was the first president of the United States married?
In the given sentence, "Who was the first president of the United States?" the word "who" is used as the subject of the verb "was". Therefore, the correct choice is "Who."