Which compound is an Arrhenius base (i.e., produces $O^H$ in aqueous solution)?

• A. $N{a}_{O}H$
• B. $C{O}_2$
• C. $N{a}_{C}l$
• D. $HCl$

Answer: (A)

Verified step by step guidance

1. Recall the definition of an Arrhenius base: it is a substance that increases the concentration of hydroxide ions (OH\textsuperscript{-}) when dissolved in water.
2. Examine each compound to determine if it produces OH\textsuperscript{-} ions in aqueous solution:
3. 1. NaOH (sodium hydroxide) dissociates completely in water to give Na\textsuperscript{+} and OH\textsuperscript{-} ions.
4. 2. CO\textsubscript{2} (carbon dioxide) dissolves in water to form carbonic acid (H\textsubscript{2}CO\textsubscript{3}), which is acidic, not basic.
5. 3. NaCl (sodium chloride) dissociates into Na\textsuperscript{+} and Cl\textsuperscript{-} ions, neither of which produces OH\textsuperscript{-} ions.
6. 4. HCl (hydrochloric acid) dissociates to produce H\textsuperscript{+} ions, making the solution acidic, not basic.
7. Therefore, identify the compound that produces OH\textsuperscript{-} ions in water, which matches the Arrhenius base definition.