I rarely ever look through the reopen queue any more, but today I did.
I found a question that seems to be highly controversial of whether it should be open or closed:
What gas has the highest refractive index?
To give you some more perspective. The first round of 'too broad' review was initiated on 2017/11/28 and failed with 3 Leave Open and 2 Close votes (review). The votes then aged away. (It gained an answer after that.)
For reasons I cannot figure out, it entered the review queue a second time on 2017/12/6. This time it succeeded (2017/12/14) with 2 Leave Open and 4 Close votes (review).
One day later (2017/12/15) it entered the reopen review process. (Still going on.)
Obviously, since my vote is binding, I am hesitant to do anything here.
I would like to figure out the reason for it being too broad, as well as the reason for not. If some of the participating users could comment (I mean write an answer) on their reasoning; preferably how this question could be improved to better fit our scope.
Currently Max's comment offers some insight. I think, however, that (1) of these restrictions could be inserted without much trouble.
(1) For whatever gas it will surely depend on the temperature and pressure. So no real theory to predict it is a matter of looking RI for various gases at that temperature and pressure. (2) Would a supercritical fluid be within scope? For a gas there is not going to be a great density hence fairly small refractive index. With a supercritical fluid you'd have a lot more matter at the solid surface of a planet. – MaxW
I can follow that logic and agree to an extent. I'd also like to hear counter arguments.
N.B.: In general - and that is probably no news to most of you - I would rather err on the keep open side than completely preventing further answers. Always keep in mind, that this question is here to stay, there is basically no reason why it couldn't be the best version of itself.