Final answer:
CH₃COOH (acetic acid) is the weak electrolyte among the given compounds as it partially dissociates into ions in solution, unlike the others which are either strong electrolytes or nonelectrolytes.The correct option is D.
Step-by-step explanation:
The compound that is a weak electrolyte out of the given options is CH₃COOH (acetic acid). Weak electrolytes are substances that partially dissociate into ions when dissolved in water. Strong electrolytes dissociate almost completely into ions, while nonelectrolytes do not produce ions in solution. In this case, BaCl₂ is a strong electrolyte because it is highly ionic and dissociates completely in water. CH₃OH (methanol) is a nonelectrolyte as it doesn't produce ions when it dissolves in water. KOH (potassium hydroxide) is a strong base and therefore a strong electrolyte. Acetic acid (CH₃COOH), however, only partially dissociates, making it a weak electrolyte.