Which property best indicates that a compound contains an ionic bond? it is insoluble in water. it can be easily flattened. it has a low boiling point. it conducts electricity when molten.

Answer is:  it conducts electricity when molten.

Ionic bond is the electrostatic attraction between oppositely charged ions (cations and anions).

Substances with ionic bond conduct an electric current in liquid, because in liquids ions are mobile, contrary to solids where ions are fixed.

For example, sodium chloride (NaCl) dissociates on ions when is molten:

NaCl(l) → Na⁺(l) + Cl⁻(l).

Compounds with the ionic bonds have high boiling points, because ionic bond is strong and they are mostly soluble in the water.

elements make up everything, and they combine to make compounds.

the answer is c