Which chemical equation represents a precipitation reaction? A. Mg (ClO3) 2 (aq) + 2HCl (aq) → MgCl2 (aq) + 2HClO3 (aq) B. AlBr3 (aq) + 3LiI (aq) → AlI3 (aq) + 3LiBr (aq) C. NH4NO3 (aq) + HBr (aq) → NH4Br (aq) + HNO3 (aq) D. Li2CO3 (aq) + FeCl2 (aq) → 2LiCl (aq) + FeCO3

Answer is D.

Among the given options, the products of equation A, B and C are aqueous solutions. Those are indicated by using (aq).

The balanced equation for the reaction between Li₂CO₃ (aq) and FeCl₂ (aq) is Li₂CO₃ (aq) + FeCl₂ (aq) → 2LiCl (aq) + FeCO₃ (s)

LiCl is a salt while FeCO₃ is a Grey/green color precipitate. Hence, option D represents a precipitation reaction.