It would be potassium chloride or kcl
What they have in common is that they both have the same number of atoms.
To balance the the chemical reaction, the number of moles
per element is balance is both side of the reaction and also the charge in both
sides of the reation. to balnce the reaction:
S2O3 2- + Cu 2+ ---> S4O6 2- + Cu+
2S2O3 2- + Cu 2+ ---> S4O6 2- + Cu+ + e
1.3 x 10^21 atoms Na is 4.63230769231 mol Na
4.63230769231 mol Na * 23g/mol Na = 106.543076923g
Your answer is C. its level of dissolved minerals ~A