Which of the following substances is a nonelectrolyte?

• A. NaCl (sodium chloride)
• B. KNO3 (potassium nitrate)
• C. HCl (hydrochloric acid)
• D. C6H12O6 (glucose)

Answer: (D)

Verified step by step guidance

1. Understand what an electrolyte is: Electrolytes are substances that dissociate into ions when dissolved in water, allowing the solution to conduct electricity.
2. Identify the nature of each substance: NaCl, KNO3, and HCl are all ionic compounds or strong acids that dissociate completely into ions in aqueous solution, making them strong electrolytes.
3. Recognize that C6H12O6 (glucose) is a molecular compound that dissolves in water but does not dissociate into ions; it remains as intact molecules in solution.
4. Conclude that since glucose does not produce ions in solution, it does not conduct electricity and is therefore classified as a nonelectrolyte.
5. Summarize: The key difference is whether the substance produces ions in solution (electrolyte) or not (nonelectrolyte).