What solution can you add to of the mixture of sr2 + (aq) and hg22 + (aq) to precipitate one cation while keeping the other cation in solution?

We can use any solution containing chloride ions as NaCl solution or even dilute HCl due to mercurous Hg₂²⁺ is from group I cations which precipitated as chloride while Sr²⁺ is from group V

Net ionic equation:

Hg₂²⁺ + 2 Cl⁻ → Hg₂Cl₂ (white precipitate)

while SrCl₂ is soluble salt