\textbf{228 --} In a hydrochloric acid solution, if the molar concentration of hydronium ions is $4\times10^{-8}$ times the molar concentration of hydroxide ions, the pH of this solution is:
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(1) $2/3$ \hfill (2) $2/7$ \hfill (3) $3/3$ \hfill (4) $3/7$
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