A. Solutions of Pb(NO₃)₂ and KBr are mixed a precipitate of PbBr₂ forms.
B. LiOH solution and HI solution are mixed and H₂O (l) forms.

C. Solutions of FeCl₃ and Na₂CO₃ are mixed and a precipitate of Fe₂(CO₃)₃ forms.

D. Aqueous solutions of HClO₄ and K₂CO₃ are mixed and CO₂ (g) and H₂O (l) are formed.