A simple test to distinguish between Cl- and SO42- ions in solution is to add a few drops of barium chloride (BaCl2) solution to each solution. If a white precipitate forms in one of the solutions, it indicates the presence of SO42- ions, as BaSO4 is insoluble in water. If no precipitate forms, it suggests the presence of Cl- ions.

The reactions that take place are as follows:

For Cl- solution:

BaCl2(aq) + 2NaCl(aq) → No reaction (all compounds are soluble)

For SO42- solution:

BaCl2(aq) + Na2SO4(aq) → BaSO4(s)↓ + 2NaCl(aq)

So, the formation of a white precipitate indicates the presence of SO42- ions, while the absence of a precipitate suggests the presence of Cl- ions in the solution.