What is classified as an electrolyte?

An electrolyte is defined as a substance that produces ions when dissolved in water, allowing it to conduct electricity. This process is crucial because the presence of free-moving charged particles—ions—is what enables electrical conductivity. When an electrolyte dissolves, it dissociates into its constituent ions, which can move freely in the solution and carry an electric current.

For instance, common electrolytes like sodium chloride (table salt) dissolve in water to form sodium and chloride ions, which are essential for various physiological functions in the body, such as muscle contraction and nerve impulse transmission. The ability of a substance to generate ions when dissolved in a solvent makes it a key player in many chemical and biological processes that depend on electrical charge.

Other substances mentioned in the options do not fit the definition of an electrolyte. A quickly evaporating substance does not necessarily produce ions and may not be ionic in nature. A gas that forms in reactions, while it may have relevance in certain chemical contexts, does not provide ions for conductivity. Lastly, a solid compound that does not dissolve in water cannot produce ions in solution and therefore cannot be considered an electrolyte.