What is the mechanism by which spin isomers of hydrogen switch between the ortho and para forms?
If such a mechanism exists, why does ortho-hydrogen not increase in concentration on increasing temperature?
Edit: The question focuses on the how of the transition - in effect, asking about the mechanism, and if there isn't one, why, and not on why the transitions take place.
Edit(II) : Please keep in mind that I'm a high schooler. Please expain in a way that would be understandible, at least with effort, not something that requires me to know, say, grad-level chemistry.