Interrogative adjectives are words placed before a noun to ask a question about that noun. In English, the main interrogative adjectives are "which," "what," and "whose." They are different from interrogative pronouns because they always modify a noun. The answer usually identifies or specifies the noun being asked about.

"Which" is used as an interrogative adjective to ask for a specific choice or selection from a known set. It appears directly before the noun it modifies. The question expects the listener to choose or identify one or more items from a limited group.

Rule
Use "which" before a noun when asking for a selection from a known set.
"Which" modifies a noun and signals that the set of options is limited or defined.

"What" is used as an interrogative adjective to ask about the identity, kind, or category of a noun. It appears before the noun when the set of possible answers is open or not clearly limited. The question usually seeks information that defines or describes the noun.

Rule
Use "what" before a noun when asking about kind or identity without a defined set.
"What" modifies a noun and signals that the options are broad or unspecified.

"Whose" is used as an interrogative adjective to ask about possession or ownership of a noun. It appears before the noun it modifies. The question expects an answer identifying the owner or possessor of the noun.

Rule
Use "whose" before a noun to ask who owns or possesses that noun.
"Whose" modifies a noun and forms a question about possession.

The interrogative adjectives "which," "what," and "whose" form the core set for asking questions about nouns in English. Each one directs the question toward selection, kind, or possession. Their meaning stays stable when they are used directly before a noun.

Word/Phrase	Definition
which	An interrogative adjective that asks for a selection from a known set.
what	An interrogative adjective that asks about kind or identity with an open set.
whose	An interrogative adjective that asks about possession or ownership.