The precipitate formed when mixing potassium carbonate (K₂CO₃) and nickel(II) chloride (NiCl₂) is nickel(II) carbonate (NiCO₃).

Here's why:

* Reaction: The reaction is a double displacement reaction where the cations and anions switch partners.

* Equation:

K₂CO₃ (aq) + NiCl₂ (aq) → NiCO₃ (s) + 2KCl (aq)

* Solubility: Nickel(II) carbonate is insoluble in water, making it the precipitate. Potassium chloride is soluble and remains in solution.