One document for each pair of Q&A.
One document for all pairs of Q&A in one chapter.
Each document will have an automatic chapter number. In InDesign one document can contain only a Chapter in the term of InDesign.
You can use the Chapter as automatic number in a paragraph style. The automatic number comes from the current level = ^# .
The very same document has to contain Question and Answer. Because this is the same document, it has to have the same chapter. It has to be part of the same list (here q&a)
When it comes to the answers, it should be a level below. The numeric place holder has to be the same as the question, here Level 1 = ^1 .
And when it comes to a second question in the same chapter, the number will increase.
With the keep options in the Paragraph Style you can determine that ever answer or question has to start with a new/even/odd page/frame.