Final answer:
Potassium chloride is an electrolyte, fructose and isopropyl alcohol are nonelectrolytes, and magnesium hydroxide is an electrolyte.
Step-by-step explanation:
1. Potassium chloride is an ionic compound and when it dissolves in water, its ions separate, making it an electrolyte.
2. Fructose is a molecular compound, and when it dissolves in water, it does not produce ions. Therefore, it is a nonelectrolyte.
3. Isopropyl alcohol is an organic molecule and its bonding is all covalent. When isopropyl alcohol dissolves in water, it separates into individual molecules but not ions. Thus, it is a nonelectrolyte.
4. Magnesium hydroxide is an ionic compound, so when it dissolves, it dissociates into ions, making it an electrolyte.