Which of the following substances is a strong electrolyte?

• A. NH_3
• B. Ba(OH)_2
• C. CH_3COOH
• D. C_{12}H_{22}O_{11}

Answer: (B)

Verified step by step guidance

1. Understand what a strong electrolyte is: a substance that completely dissociates into ions when dissolved in water, resulting in a solution that conducts electricity very well.
2. Analyze each substance given: NH_3 (ammonia) is a weak base and does not fully ionize in water, so it is a weak electrolyte.
3. CH_3COOH (acetic acid) is a weak acid and only partially ionizes in water, making it a weak electrolyte.
4. C_{12}H_{22}O_{11} (sucrose) is a molecular compound that does not ionize in water, so it is a nonelectrolyte.
5. Ba(OH)_2 (barium hydroxide) is a strong base that dissociates completely into Ba^{2+} and OH^{-} ions in water, making it a strong electrolyte.