Which of the following is an example of an electrolyte?

An electrolyte is a substance that, when dissolved in water, dissociates into ions and conducts electricity. A salt solution serves as a prime example of an electrolyte because when salts like sodium chloride are dissolved in water, they breakdown into their respective ions (sodium and chloride ions). These free ions enable the solution to conduct electricity, which is a defining characteristic of electrolytes.

Oxygen gas, carbon dioxide, and pure water do not fulfill the criteria for electrolytes in the same way. Oxygen gas exists as a molecular form and does not dissociate into ions when introduced into a solution. Carbon dioxide can react with water to form carbonic acid, but it does not produce ions that can conduct electricity effectively in the same manner as a salt solution. Pure water, while it can conduct a very small amount of electricity due to the autoionization process, is considered a very weak electrolyte because the concentration of hydrogen and hydroxide ions is extremely low compared to that of a salt solution. Thus, the presence of dissolved ions in a salt solution clearly makes it the correct example of an electrolyte.