Here's why:

* Reaction: When silver nitrate (AgNO₃) and sodium chloride (NaCl) are combined, they undergo a double displacement reaction.

* Products: The products of this reaction are silver chloride (AgCl) and sodium nitrate (NaNO₃).

* Solubility: Silver chloride is insoluble in water, meaning it doesn't dissolve and forms a solid precipitate. Sodium nitrate, on the other hand, is soluble in water.

Therefore, the solid that forms is silver chloride, the precipitate.