Final answer:
A good electrolyte when dissolved in water is a substance that fully dissociates into ions, and such substances are known as strong electrolytes. Examples include soluble ionic compounds, strong acids, and strong bases.
Step-by-step explanation:
A good electrolyte when dissolved in water is a substance that dissociates almost completely into ions, which makes it a strong electrolyte. Examples of strong electrolytes include all soluble ionic compounds, strong acids like HCl, HBr, HI, H₂SO₄, and strong bases. These substances produce a high concentration of ions in solution, enabling it to conduct electricity very effectively.
For instance, potassium chloride (KCl) is a soluble ionic compound that when dissolved in water, dissociates completely into potassium (K+) and chloride (Cl-) ions, making it a strong electrolyte. Similarly, magnesium hydroxide [Mg(OH)₂], another ionic compound, is a strong base and therefore also qualifies as a strong electrolyte. On the other hand, substances like fructose (C₆H₁₂O₆) and isopropyl alcohol [CH₃CH(OH)CH₃] do not dissociate into ions and are considered nonelectrolytes.