Usually 24 hours but sometimes more than that if admin is busy in some other work.
@zeeshunjutt777 most of the Q&A questions are pending til @admin approves them in the mornings.
Now it depends on your time zone as I am in the US and I go by Central US Time.
So it all depends on time and for weekends their could be delays.
I would say Please be Patient.
I am not sure on this one @zeeshunjutt777 as your question here has come after your question that has not been approved.
So I am thinking that the question you asked before that is not approved will not be approved.
I will agree with @ardodd’s statement. He is 100% correct for his answer. As your this (current question) has been approved. And the previously asked questions are not approved. So, I think, all of those questions have rejected.
Usually it takes 24hours for approval of your question but some times it even takes more so all is you have to be patient till admin approves it.
I have also heard from somewhere that question approval take up to 24 hours. But, the truth is that I am still waiting for my question to be approved from @admin from the last 3-4 days.
According to rules and regulations a Question may take up to 24 hours to approve.