An electrolyte is the substance that is able to conduct electricity. Electricity is the flow of charged particles. Therefore, in order to be an electrolyte, we need to have charged particles.
We can memorize 3 types of substances that are electrolytes: metals, ionic compounds dissolved in water and strong acids/bases. To be an ionic compound, we must have a metal and a nonmetal. Looking at the answer choices we see nonmetals only. To search for strong acids and bases we can look at the Reference Table K. We can see that H2SO4 is a strong acid and therefore an electrolyte. Choice (4) is the correct answer.
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