Interrogative Pronouns
The practical task is deciding what the question word stands for and what job it performs. “Which” and “what” differ in how choices are framed, while “who/whom” can reflect subject/object role and register.
Interrogative pronouns such as “who,” “whom,” “whose,” “what,” and “which” stand in for the unknown person or thing being asked about. Their choice depends on meaning and grammatical role, and some of the same forms can also function as determiners or relative pronouns.
Key details
Important caveats
Boundary
In “which book,” “which” is used with a noun; in “Which do you want?” it stands pronominally. Relative uses are a separate construction.
Further guidance
Choice And Role
Use meaning and grammatical role to choose among who/whom/whose and what/which; formality can affect whether “whom” is natural.
Diagnostic
Ask whether the question word itself occupies a noun-phrase role or instead modifies a following noun.
Worked Example
“Who called?” uses “who” as the subject of the question. “Which do you prefer?” uses “which” pronominally to ask about a restricted set of alternatives.
Sources and evidence
Sources are shown with the role they play in this guide. Historical or style-sensitive claims are kept within the evidence boundary described above.
- Questions: interrogative pronouns (what, who) (opens in a new tab)Cambridge University Press · Cambridge identifies who, which, whom, what, and whose as interrogative pronouns and explains subject/object uses plus who/whom and what/which distinctions.
- Pronouns (opens in a new tab)Cambridge University Press · Cambridge lists interrogative pronouns as a pronoun category and distinguishes pronouns from determiners that can sometimes be used pronominally.