Which property best indicates that a compound contains an ionic bond?

• A. It is a poor conductor of electricity in the solid state.
• B. It has a low melting point.
• C. It is insoluble in water.
• D. It conducts electricity when dissolved in water.

Answer: (D)

Verified step by step guidance

1. Understand the nature of ionic bonds: Ionic bonds form between metals and nonmetals through the transfer of electrons, resulting in positively and negatively charged ions.
2. Recall the properties of ionic compounds: They typically have high melting points, are soluble in water, and conduct electricity when molten or dissolved because the ions are free to move.
3. Analyze the options given: A poor conductor in solid state is typical for ionic compounds because ions are fixed in place; low melting point and insolubility in water are more characteristic of covalent compounds.
4. Focus on electrical conductivity: Ionic compounds conduct electricity when dissolved in water because the ions dissociate and move freely, allowing current to flow.
5. Conclude that the best indicator of an ionic bond is the ability to conduct electricity in aqueous solution, as this directly reflects the presence of free ions.