What conclusion can you draw from the scientist's observations?
A.new substance was formed, because the formation of a
precipitate is evidence that a chemical reaction took place.
B.A physical reaction took place, because the physical properties of
the substances changed.
C.The lead nitrate froze when it was added to the potassium iodide,
because solids form as a result of freezing.
D.The potassium iodide crashed out of solution, because the solution
became supersaturated, and no reaction occurred.