(a) What type of ion chromatography (cation or anion) will you use to separate

the following ions: Cu2+, Fe3+, Ag+ and Na+
.
I'm having trouble here as I know that in elution chromatography they use like charges to separate ions, but is that the same case in ion-exchange?

(b) Give the order of elution when the ions are stripped off the column with an
acidic solution. Explain your answer. (3 marks)