Substance Y is soluble only in nonpolar solvents and does not conduct electricity in solid or liquid form. Y is most probably

• A. An ionic substance
• B. A polar substance
• C. A nonpolar substance
• D. A metallic substance

Answer: (C)

The key idea here is polarity and the presence of mobile charges. Substances tend to dissolve best in solvents with similar polarity: nonpolar solutes in nonpolar solvents, polar solutes in polar solvents. Also, electrical conductivity requires free charged particles.

Since this substance dissolves only in nonpolar solvents, it’s likely nonpolar, because nonpolar molecules mix readily with other nonpolar media. The fact that it doesn’t conduct electricity in either solid or liquid form means there aren’t free ions or delocalized electrons present to carry charge. Ionic compounds would not dissolve in nonpolar solvents, and they conduct electricity when melted or dissolved in water due to free ions. Metallic substances conduct electricity as solids because of a sea of delocalized electrons. Polar covalent substances often don’t conduct electricity either, but their solubility pattern points away from polarity and toward nonpolarity in this case.

So the description fits a nonpolar substance.