Answer:
Step-by-step explanation:
A substance with an extended structure composed of a metal and a nonmetal is most likely an ionic compound. Ionic compounds have high melting and boiling points, are hard and brittle, and are good conductors of electricity in the molten or aqueous state but not in the solid state.
The high melting and boiling points of ionic compounds are due to the strong electrostatic forces of attraction between the oppositely charged ions in the crystal lattice structure. The hardness and brittleness of ionic compounds are due to the rigid and ordered structure of the crystal lattice, which tends to shatter when subjected to a force. The ability to conduct electricity in the molten or aqueous state is due to the presence of mobile ions that can carry an electrical charge.
Therefore, the most likely property of a substance with an extended structure composed of a metal and a nonmetal is a high melting and boiling point, hardness and brittleness, and the ability to conduct electricity in the molten or aqueous state.