Final answer:
The three characteristics of ionic compounds are a high melting point, they conduct electricity in a molten state, and they do not share electrons, corresponding to option C.
Step-by-step explanation:
From the list provided, the three characteristics of ionic compounds are: high melting point, conduct electricity in molten state, and do not share electrons. Therefore, the correct answer is (C) High melting point, conduct electricity in molten state, do not share electrons. Ionic compounds have a crystalline structure, are often hard and brittle, and have high melting and boiling points. These properties stem from the ionic bonds that hold the compound together, which are electrostatic forces of attraction between oppositely charged ions. While solid ionic compounds do not conduct electricity, when they are dissolved in water or melted, the ions are free to move, making ionic solutions and molten ionic compounds good conductors of electricity.