Acetic acid (CH3COOH) is a weak acid with pKa of 4.8. In a solution of pH5, if the total acetates concentration ([CH3COOH]+[CH3COO])is 2mol/L, what is the concentration of CH3COOin the solution? \begin{tabular}{c} 0.77mol/L \\ \hline 1.23mol/L \\ 0.5mol/L \\ \hline 0.006mol/L \end{tabular}