[Rutherford]

Sorry, just one last question if it's not a problem:
C=100(R_M−1)/(R_M+17) How did you get this?

[DrCMS]

To answer the question with metal oxides I get the following answers:

HX 39.71% the metal is Li while X can be F, Br or I

HX 70.933% the metal is Na while X can only be F and I think there is a 70-72% HF solution commercially available see here - http://www.chemicalland21.com/industrialchem/inorganic/HYDROFLUORIC%20ACID.htm

HX 80.875% the metal is K while X can only be F?  I'm not sure how concentrated HF solutions can go and still be stable

HX 90.363% the metal is Rb while X can only be F?