The product formed when a solution forms barium carbonate is barium carbonate (BaCO₃) itself.

Here's a breakdown:

* Barium carbonate (BaCO₃) is an ionic compound that is insoluble in water.

* When a solution containing barium ions (Ba²⁺) and carbonate ions (CO₃²⁻) react, these ions combine to form a solid precipitate of barium carbonate.

This reaction can be represented by the following chemical equation:

Ba²⁺(aq) + CO₃²⁻(aq) → BaCO₃(s)

So, the final product of the reaction is the solid barium carbonate (BaCO₃).