Final answer:
Adding 0.02 M of NaCl to the MgF2 solution increases ionic strength, as additional ions are introduced into the solution.
Step-by-step explanation:
When we add 0.02 M of NaCl to the MgF2 solution, there is an increase in ionic strength. Ionic strength is a measure of the total concentration of ions in the solution, and NaCl dissociates into Na⁺ and Cl⁻ ions, contributing to this measure. By increasing the number of ions in the solution, the ionic strength of the solution inevitably increases. This addition does not change the solvation energy directly, but it can affect how ions are solvated due to changes in the ionic environment.