So far I can say answeree is the best question and answer site where one gains points for every answer, question and a point on comment to someone's answer. At the end the points are converted into cash that can be claimed through the site administrator and are deposited in your PayPal.
The best question is up to you but i suggest answering random funny questions would be worth it and while you answer maybe even earning would be great yh I don't know
I think Quora is perhaps one of the best popular free websites where you can ask and get answers. It allows users to create social networks and follow topics that interest you.
I personally think Answeree is a good site for this purpose. There are other platforms that cater to these needs of students for their questions, such as Chegg, Course Hero, etc.
Personally I think answeree is the best questions and answers site where one earn points by answering questions and commenting then convert these points to money.