A compound is solid at room temperature, dissolves in water, and conducts electricity when dissolved. Which statement best identifies this compound?

A compound is solid at room temperature, dissolves in water, and conducts electricity when dissolved. Which statement best identifies this compound?

• A. Glucose, a covalent compound
• B. Sodium chloride, an ionic compound
• C. Glucose, an ionic compound
• D. Sodium chloride, a covalent compound

Answer: (B)

When a substance conducts electricity only after being dissolved, it indicates it forms mobile ions in solution. That behavior is characteristic of ionic compounds. In solid form, ions are locked in a lattice and don’t move, so no conduction occurs; once dissolved, the compound dissociates into Na+ and Cl− ions that carry charge through the solution. Glucose, a covalent compound, dissolves in water but does not produce free ions, so its solution does not conduct electricity. Thus, the described properties identify the compound as an ionic solid that dissociates in water, namely sodium chloride.

When a substance conducts electricity only after being dissolved, it indicates it forms mobile ions in solution. That behavior is characteristic of ionic compounds. In solid form, ions are locked in a lattice and don’t move, so no conduction occurs; once dissolved, the compound dissociates into Na+ and Cl− ions that carry charge through the solution. Glucose, a covalent compound, dissolves in water but does not produce free ions, so its solution does not conduct electricity. Thus, the described properties identify the compound as an ionic solid that dissociates in water, namely sodium chloride.