Pronouns are not only used in assertive statements but also in interrogative statements as Interrogative pronoun that is, pronouns which are used to ask questions are known as Interrogative Pronouns. Pronouns like whoever, who, which, what, where, etc., come under this type of Pronouns. Under these who, whom, whose, what and which are considered as the important ones whereas the other pronouns like whoever, whosever, whatsoever, etc., are not considered that important.
For example, What do you mean, you forgot your shades?