Which of the following is a precipitation reaction?

Question

I. 2 Mg (s) + O2 (g) → 2 MgO (s)

II. SO3 (g) + 2 H2O (l) → H3O+ (aq) + HSO4- (aq)

III. Pb2+ (aq) + CrO42- (aq) → PbCrO4 (s)

IV. 2 H2O (g) → 2 H2 (g) + O2 (g)

V. Ag+ (aq) + 2 NH3 (aq) → [Ag(NH3)2]+ (aq)

Answer 1

Which goes from aqueous to solid.

Answer 2

idk