Answer: The statement it is a weak acid is true for the substance.
Explanation:
An acid that dissociates completely when dissolved in water to give hydrogen [tex](H^{+})[/tex] or hydronium [tex](H_{3}O^{+})[/tex] ions is called a strong acid.
For example, HCl is a strong acid.
[tex]HCl + H_{2}O \rightarrow H_{3}O^{+} + Cl^{-}[/tex]
An acid that dissociates partially or weakly when dissolved in water to given hydrogen or hydronium ions is called a weak acid.
For example, [tex]CH_{3}COOH[/tex] is a weak acid.
[tex]CH_{3}COOH \rightleftharpoons CH_{3}COO^{-} + H_{3}O^{+}[/tex]
A strong base is a base which when dissolved in water then it dissociates completely to give hydroxide ions.
For example, NaOH is a strong acid.
A weak base is a base which when dissolved in water then it dissociates partially or weakly to give hydroxide ions.
For example, [tex]NH_{3}[/tex] is a weak base.
Hence, in an aqueous solution where 42% of a substance dissociates to release hydronium ions shows that the dissociation is less than 50%. This means that substance is dissociating weakly so, it is a weak acid.
Thus, we can conclude that the statement it is a weak acid is true for the substance.
