Which of the following is a strong base in water?

• A. $N{H}_3$
• B. $C{H}_{3}COOH$
• C. $NaOH$
• D. $H{2}_{}O$

Answer: (C)

Verified step by step guidance

1. Identify the substances given: NH₃ (ammonia), CH₃COOH (acetic acid), NaOH (sodium hydroxide), and H₂O (water).
2. Recall the definition of a strong base: a substance that completely dissociates in water to produce OH⁻ ions.
3. Analyze each substance's behavior in water: NH₃ is a weak base (partially accepts protons), CH₃COOH is a weak acid (donates protons), H₂O is neutral, and NaOH is a strong base (fully dissociates into Na⁺ and OH⁻ ions).
4. Use the dissociation equation for NaOH in water: \(\text{NaOH} \rightarrow \text{Na}^+ + \text{OH}^-\), showing complete ionization.
5. Conclude that NaOH is the strong base among the options because it fully dissociates to produce hydroxide ions in aqueous solution.