Interrogative adjectives are question words that come before nouns. They help you ask about a thing, a choice, or an owner. In this module, the main words are what, which, and whose.

What comes before a noun when you ask about identity, type, or category. It often gives an open question, and the answer is not limited to a small known set. Speakers sometimes use what where other speakers may use which, especially in everyday speech.

Rule
Use what before a noun when you ask about the name, kind, or type of something.
Use what when the possible answers are open and not clearly limited for the listener.
In everyday English, what can also appear in questions where the choices feel known, because real usage is sometimes flexible.

Which comes before a noun when you ask the listener to choose from a limited set. The set may be named, seen, or understood from the situation. In some contexts, which sounds more specific than what, but speakers do not always make a strict difference.

Rule
Use which before a noun when the answer comes from a limited number of options.
Use which when the options are already clear from the conversation or situation.
Which often shows selection more clearly than what, but the difference is not always strict in natural English.

Whose comes before a noun to ask about possession or ownership. It asks who something belongs to. It can sound more formal to some speakers, but it is normal and correct in everyday English.

Rule
Use whose before a noun to ask who owns something.
Whose asks about possession, not about the type or identity of the noun.
Whose is used with singular and plural nouns when you ask about an owner.

Interrogative adjectives come directly before nouns in questions. The noun stays with the question word as one group, such as what book, which bus, or whose bag. This group is part of the question pattern.

Word or Phrase	Definition
what book	This phrase places what before the noun book to ask about type or identity.
which bus	This phrase places which before the noun bus to ask for a choice from known options.
whose bag	This phrase places whose before the noun bag to ask about ownership.

You can now identify and use interrogative adjectives before nouns. You can use what for open questions, which for selection from limited options, and whose for possession. You also know that natural English can be flexible, so what and which may sometimes overlap.