An aqueous solution of an unknown solute is tested with litmus paper and found to be acidic. The solution is weakly conducting compared with a solution of \(\mathrm{NaCl}\) of the same concentration.Which of the following substances could the unknown be: \(\mathrm{KOH}, \mathrm{NH}_{3}, \mathrm{HNO}_{3}, \mathrm{KClO}_{2}, \mathrm{H}_{3} \mathrm{PO}_{3}, \mathrm{CH}_{3} \mathrm{COCH}_{3}\) (acetone)?

Among the substances listed, we need to find those that have acidic properties. Recall that acidic substances increase the concentration of hydrogen ions (\(\mathrm{H}^{+}\)) in the solution. We can identify these substances based on their chemical formulas, specifically those that can donate an \(\mathrm{H}^{+}\) ion. Below, we list the substances and their acidic properties: - \(\mathrm{KOH}\): Not acidic (basic) - \(\mathrm{NH}_{3}\): Not acidic (basic) - \(\mathrm{HNO}_{3}\): Acidic - \(\mathrm{KClO}_{2}\): Not acidic (neutral salt) - \(\mathrm{H}_{3}\mathrm{PO}_{3}\): Acidic - \(\mathrm{CH}_{3} \mathrm{COCH}_{3}\) (acetone): Not acidic From this analysis, we find that \(\mathrm{HNO}_{3}\) and \(\mathrm{H}_{3}\mathrm{PO}_{3}\) are acidic substances and could be the unknown acid in the solution.

Now that we have identified the acidic substances, we will need to consider their conductivity properties. Remember that the unknown solution is weakly conducting compared to a solution of \(\mathrm{NaCl}\). Thus, the substance that can form an acidic solution with weaker conductivity than \(\mathrm{NaCl}\) is the most likely candidate. - \(\mathrm{HNO}_{3}\): A strong acid, which will dissociate completely in water and produce a high concentration of ions, resulting in a relatively high conductivity. This does not match the description of the unknown solution. - \(\mathrm{H}_{3}\mathrm{PO}_{3}\): A weak acid, which will partially dissociate in water and produce a low concentration of ions, resulting in a relatively low conductivity. This aligns with the property of the unknown solution that states it has weaker conductivity than the \(\mathrm{NaCl}\) solution. It can be concluded that among the given substances, the unknown solution could be \(\mathrm{H}_{3}\mathrm{PO}_{3}\).