Question

Based on the Arrhenius theory, when potassium
hydroxide dissolves in water, the only negative
ion in the aqueous solution is
(1) O2 (aq) (3) H (aq)
(2) OH2 (aq) (4) OH (aq)

Answer 1

(4)  $OH^{-}$ (aq)

That's the answer.

Answer 2

Answer : The correct option is, (4) $OH^-(aq)$.

Explanation :

According to the Arrhenius theory, an acid is a substance that ionizes in water to gives $H^+$ ions (hydronium ions or hydrogen ions) and a base is a substance which ionizes in water to gives $OH^-$ ions (hydroxide ions).

As we know that when the potassium hydroxide (KOH) dissolves in water or ionizes in water to gives $OH^-$ ions (hydroxide ions) and $K^+$ ions (potassium ion). That means $OH^-$ ion is a negative ion in aqueous solution and $K^+$ ions is a positive ion in aqueous solution.

Hence, the correct option is, (4) $OH^-(aq)$.