Im afraid that they will not make any isotopes for elements. This may be rejected.
I believe noble gas is helium or all the noble gases into one element.
As NUCLEAR_FOX already said, helium exists as NBLE,
And we already have uranium-235 in the game, it's just called plutonium.
Not sure if you're trolling? TPT is not meant to be realistic at all, that would be boring and would break saves possibly.
Yes, indeed. NBLE is helium. I even have a save that explains that.