A solid sample of a compound and a liquid sample of the same compound are each tested for electrical conductivity. Which test conclusion indicates that the compound is ionic?
(1) Both the solid and the liquid are good conductors.
(2) Both the solid and the liquid are poor conductors.
(3) The solid is a good conductor, and the liquid is a poor conductor.
(4) The solid is a poor conductor, and the liquid is a good conductor.
Answer and Explanation: Ionic compounds have unique properties when it comes to their electrical conductivity. As a solid an ionic compound can not conduct electricity. Therefore, choices 1 and 3 are incorrect.
When an ionic compound is melted or is dissolved in water it is able to conduct electricity because of the freed up charged ions. Thus, choice 4 is the correct answer.
P.S. Metals are good conductors of electricity in both solid and liquid forms.
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