Analysis of an unknown substance indicates that it is a brittle solid. It acts as an electrical insulator (does not conduct) as a solid but conducts electricity when melted. Which of the following substances would have these characteristics? a. HCl
b. Al
c. KBr
d. SiF4
e. I2

KBr

Explanation:

A metal has a very high melting point. Aluminum is a metal.

Ionic solids do not conduct electricity in the solid state. However, when the solids are melted, they conduct electricity.

KBr is an ionic substance, it can only conduct electricity in molten form because the ions are locked up in the solid.