[LHM]

A mixture of which 0.2M aqueous solutions will form a precipitate that dissolves in 6 M nitric acid?

A) Co(NO₃)₂ and NH₄Cl
B) Pb(NO₃)₂ and NaBr
C) Ba(NO₃)₂ and Na₂CO₃
D) Al(NO₃)₃ and K₂SO₄

I see why it's not A or D. As for why it's not B though, is it because HBr is a strong acid so PbBr₂ won't dissolve in nitric acid? And then CO₃^2- wants protons, so it dissolves to get them? Or is there a different reason?

[nj_bartel]

Have you learned LeChatlier's Principle?