Which of the following substances is NOT an electrolyte?

• A. HCl (hydrochloric acid)
• B. NaCl (sodium chloride)
• C. C_6H_{12}O_6 (glucose)
• D. KNO_3 (potassium nitrate)

Answer: (C)

Verified step by step guidance

1. Understand what an electrolyte is: an electrolyte is a substance that dissociates into ions when dissolved in water, allowing the solution to conduct electricity.
2. Examine each substance to determine if it dissociates into ions in aqueous solution:
3. HCl (hydrochloric acid) is a strong acid that ionizes completely into H\_3O\^+ and Cl\^- ions, so it is an electrolyte.
4. NaCl (sodium chloride) is an ionic compound that dissociates into Na\^+ and Cl\^- ions in water, making it an electrolyte.
5. C\_6H\_{12}O\_6 (glucose) is a molecular compound that dissolves in water but does not ionize into ions, so it does not conduct electricity and is NOT an electrolyte.