Question

separate Pb +2, Cu+2, Ag+ and Ba+2 mixed together
you have only NH3, HNO3, H2SO4, HCl, NaOH, AgNO3, BaNO3 to work with

Answer 1

Pb +2, Cu+2, Ag+ and Ba+2

initially

Add HCl, so Pb+2 and Ag+ ions precipitate:

Pb+2 + 2Cl- = PbCl2(s)

Ag+ + Cl- = AgCl(s)

Filter this and le tthe aqueous solution for other separation

For the precipitates:

add NH3 enough, so Ag forms Ag(NH3)4 + complex --> which is soluble, PBCl2(s) remains...

Filter PbCl2(s) and then

this is now:

Pb+2 and Ag+ separated...

b)

Cu+2 and Ba+2 mix:

for Cu+2

Add H2S in acidic media

S-2 + Cu+2 = CuS(s)

filter, and separate CuS from solution

c)

Solution is now Ba+2 alone...

This can be obtained via precipitation

Ba+2 + H2SO4 --> BaSO4(s)