An interrogative determiner is a word that modifies a noun by asking a question. Interrogative determiners were called "interrogative adjectives" in traditional grammar. Interrogative determiners like what, which, whose etc.

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There are three interrogative determiners in English:

·         What – asking a question about a thing or things

·         Which – asking a question about a thing or things

·         Whose – asking a question about possession

Examples:

What

1. What time is it?
2. What is she doing?
3. What are you cooking for dinner?

Notice that in the following examples, 'what' is a pronoun, not a determiner.

1.   What do you do for a living? 

2.   What is your name? 

Which

1. Which pen do you want to buy?
2. Which classes are you taking?
3. Which book did you like the best?

Whose

1. Whose car are you driving?
2. Whose books are these?
3. Whose pen is this?

Note: Do not confuse “whose” and “who’s”. We use “whose” to ask a question about a possession.

Incorrect- who’s book is this?

Correct- whose book is this?

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