An excess of aqueous ammonia is added to three different flasks ( F₁, F₂, F₃ ) containing aqueous solutions of CuSO ₄, Fe ₂ ( SO ₄ )₃ and NiSO ₄ respectively. Which of the following is correct about this addition? I. A precipitate will be formed in all three flasks II. Ammonia acts as a base as well as a ligand exchange reagent in F₁ and F₃ III. A soluble complex of NH ₃ and the metal ion is formed in F ₁ and F ₃ IV.