Answer:
the solubility of the ionic solid decreases
Step-by-step explanation:
If a salt MX is added to an aqueous solution containing the solute AX, the X^- ion is common to both of the salts. The presence of X^- in the solution will suppress the dissolution of AX compared to the solubility of AX in pure water. This observation is known as common ion effect in chemistry.
The origin of common ion effect is based on Le Chatelier's principle. The addition of a solute will drive the equilibrium position towards the left hand side.