explain how you would develop a scheme to separate and identify ag, pb, fe,and al in a solution that might contain all four as ions
Surely you don't want us to write out the scheme for you. That's a qual problem. Depending upon how complicated you want to make it it could take an hour or two.I can give you some hints.
Adding dilute HCl will ppt Ag and Pb as AgCl and PbCl2. PbCl2 is soluble in hot water, AgCl is soluble in NH3. Fe and Al are not affected by the HCl. Then adding NaOH will ppt both Al and Fe as the hydroxides but Al is soluble in excess NaOH whereas Fe(OH)3 is not.l