5

When a question has (at least) an answer, it remains always visible, even if it is closed.

On the contrary, closed questions with no answers, as far as I know, after some time are no more visible.

Does it happen also when a question is marked as duplicate and has no answer? Or does it remain as it could be useful for future users, if they search for the same problem but with the words of the duplicate question?

5

It can happen, depending on the post score and whether the user is still present. Specific details on when/how posts are deleted is available here:

How does deleting work? What can cause a post to be deleted, and what does that actually mean? What are the criteria for deletion?

3

It does not look like it.

This could of course be subject to policy changes, but skimming through the pages of search results I could not find any gaps. (Only the text at the top of the questions changed a few times.)

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .