Final answer:
The reaction of barium chloride dihydrate with sodium phosphate dodecahydrate forms a precipitate, specifically barium phosphate, which is insoluble in water. The correct option is (A).
Step-by-step explanation:
When barium chloride dihydrate reacts with sodium phosphate dodecahydrate, a precipitate is typically formed.
This type of reaction is a double displacement reaction, where the cations and anions of the reactants switch places, leading to the formation of new compounds, one of which is often insoluble in water and precipitates out.
For example, when barium chloride reacts with a sulfate compound, like sodium sulfate, barium sulfate precipitates.
To answer the question specifically, the reaction of barium chloride dihydrate with sodium phosphate dodecahydrate creates a precipitate of barium phosphate, which is insoluble in water. So the correct answer to the question would be option A: Creates a precipitate.