What Are The WH Questions Called?
An interrogative word or question word is a function word used to ask a question, such as what, which, when, where, who, whom, whose, why, whether and how. They are sometimes called wh-words, because in English most of them start with wh- (compare Five Ws).
Wh-questions begin with what, when, where, who, whom, which, whose, why and how. We use them to ask for information.
wh- questions - English Grammar Today - Cambridge Dictionary
What part of speech are Wh-questions?
The question words or wh-words are relative pronouns and interrogative pronouns in part of speech. A relative pronoun relates to some noun or other pronoun going before in the sentence.
What part of speech are question words? - Quora