please answer all if possible !

7. A sample of coal mine drainage with pH 2.5 from SE Ohio has the following composition: Constituent Conc. (mg/L) A13+ 26 Fe3+ 43 Ca2+ 200 Mg2+ 86 K 3.0 Nat 9.1 SO42 1400 CH 9 HCO3 0 (a) Calculate the concentration of each constituent in molar units and equivalent units (where equivalent units are defined by # charges per mole) (b) Calculate the total dissolved solids, TDS, (in mg/L) of the water sample (c) Calculate the hardness (in mg/L CaCO3), where hardness refers to the summation of the concentrations of multivalent cations (d) Water must be "electrically neutral", meaning the sum of the concentration of the positively charged species must equal the sum of the concentration of the negatively charged species. Is this water electrically neutral? If not, what could be the source of error