Interrogative

We use interrogative pronouns to ask questions:

e.g. Who is that man?

Whom did you phone?

Whose is this pencil?

What's the time?

Which is your favourite season? (= we know exactly how many seasons there are)

By the way, some of these pronouns make compounds with 'ever' (whatever, whatsoever, whoever, whichever), to show confusion or surprise.