Dilution means adding more solvent to a solution to lower down its concentration and in that process volume of solution expands. That means on diluting a solution the following parameters will change:
1. Amount of solvent
2. Total volume of the solution
3.Concentration of the solution
So the parameter that does not change is the amount of solute that will remain constant on diluting a solution, So here the the answer will be the amount of solute that will remain unchanged during dilution.
