Answer: Option (3) is the correct answer.
Explanation:
In an aqueous solution, a compound exists in the form of ions that is in the form of protons and electrons.
Protons are positively charged and electrons are negatively charged. A proton (usually hydrogen ion, [tex]H^{+}[/tex]) in water (solvent) also exists as [tex]H_{3}O^{+}[/tex].
For example, [tex]H_{2}O + HCl \rightleftharpoons H_{3}O^{+} + Cl^{-}[/tex]
This shows that the conjugate acid of [tex]H_{2}O[/tex] is [tex]H_{3}O^{+}[/tex].
Thus, we can conclude that a hydrogen ion, H+, in aqueous solution may also be written as [tex]H_{3}O^{+}[/tex].
