which characteristic(s) makes ionic compounds useful as a building material?\nlow melting and boiling…

Brief Explanations:

Ionic compounds have strong ionic bonds which give them hardness. Their brittleness can also be utilized in building - materials in certain applications. Low melting and boiling points would make them unsuitable for building. Their ability to conduct electricity in molten or aqueous state is not related to their use as building - materials. Many ionic compounds dissolve in water, and this is not a characteristic that makes them useful as building - materials.

Answer:

hardness and brittleness