Classify each statement as a fact, law, or hypothesis. the ashes from a campfire weigh less than the wood from which they were produced because fire causes atoms to weigh less. all samples of a pure substance melt at the same temperature under a given set of conditions. a certain piece of glass, when heated in an open flame to a temperature near its melting point, imparts a yellow color to the flame. metal objects, when thrown out a window, always fall to the ground.