wh questions are open questions, they leave room for a description or opinion, and are more useful in eliciting information.

 


what - when you are asking for information about something.
who or whom when you are asking about someone's identity.
whose - ask about possession.
why - ask for a reason.
how - ask about the way in which something is done.
when - ask about the time that something happened or will happen.
where - ask questions about place or position.
which - when you are asking for information about one of a limited number of things.