Final answer:
Non-conductivity in the molten state is the least characteristic property of typical ionic compounds, as they usually conduct electricity when molten or dissolved.
Step-by-step explanation:
The property that is least characteristic of typical ionic compounds is D) Non-conductivity in molten state. Ionic compounds typically have high melting and boiling points, are soluble in water, and are brittle when solid. However, when it comes to electrical conductivity, ionic compounds are known to conduct electricity well when they are either molten or dissolved in water, contrary to non-conductivity in the molten state which is not characteristic of them.