Ionic compounds dissolved in water conduct an electric current due to the presence of freely moving ions in the solution. When an ionic compound, such as sodium chloride (NaCl), is dissolved in water, the compound dissociates into its constituent ions—sodium (Na+) and chloride (Cl−) ions—a process known as ionization. These ions become solvated by water molecules, surrounding themselves with water molecules which reduces electrostatic attractions between ions.

When an electric current is passed through the solution, these solvated ions can move freely towards the oppositely charged electrodes. The positively charged sodium ions (cations) move towards the cathode (negative electrode), while the negatively charged chloride ions (anions) move towards the anode (positive electrode). This movement of ions constitutes an electric current flowing through the solution.

Therefore, the presence of freely moving ions in the solution allows ionic compounds dissolved in water to conduct an electric current.