Final answer:
Soluble ionic compounds dissociate nearly completely in water into ions which are surrounded by water molecules, leading to the conclusion that they are strong electrolytes capable of conducting electricity.
Step-by-step explanation:
When soluble ionic compounds are placed in water, their ions separate and disperse uniformly throughout the solution. This occurs because water molecules surround and solvate the ions, effectively reducing the strong electrostatic forces that hold the ions together in a solid. This process is identified as dissociation, which is a type of physical change. As a result, these ionic compounds are known to be strong electrolytes because they dissociate nearly completely in solution, allowing the solution to conduct an electrical current due to the movement of ions.