Which of the following causes a precipitate to form?

A. Atoms combining in a solution to form a solid
B. Volcanoes erupting and magma cooling
C. Lava crystallizing
D. Minerals undergoing changes in pressure

Question

Which of the following causes a precipitate to form?
 	
	A. Atoms combining in a solution to form a solid
	B. Volcanoes erupting and magma cooling
	C. Lava crystallizing
	D. Minerals undergoing changes in pressure

anonymous · Answer

Perhaps all of them.  A for sure.  B maybe, because changes in temperature can change the solubility of substances.  C very likely, because when one substance crystallizes it normally expels any other substance that might have been dissolved in it, and D possibly, because, like changes in temperature, changes in pressure can change the solubility of substances.  However, only A absolutely MUST correspond to the formation of a precipitate.  The others may, but need not.

shane_b · Answer

Right...if there is only one answer to select, go with A.