Which is the most complete charge balance expression for a saturated solution of CaC2O4 ? [Ca2+]=[C2O42]2[Ca2+]=2[C2O42]+[HC2O4][H+]+2[Ca2+]=[OH]+2[C2O42][H+]+2[Ca2+]=[OH]+2[C2O42]+[HC2O4] How much mental effort did you expend on this question? \begin{tabular}{l|l|l|l|l|l|l} Low & 1 & 2 & 3 & 4 & 5 & High \end{tabular}