What defines an electrolyte?

An electrolyte is defined as a substance that conducts electricity when dissolved in water or when melted. This is because electrolytes dissociate into ions in solution or in a molten state, allowing electrical current to flow through the solution. The presence of free-moving charged particles (ions) is what enables the conduction of electricity.

In contrast, substances that dissolve in oil typically do not have the ability to dissociate into ions, while substances that do not dissociate in solution (like most non-electrolytes) also do not conduct electricity. Lastly, substances that are gases at room temperature do not inherently possess the properties of an electrolyte unless they can form ions in solution. Therefore, the defining feature of an electrolyte is its ability to conduct electricity by dissociating into ions in a solution, which is why the correct choice focuses on this characteristic.