Identify the mass law that each of the following observations demonstrates, and explain your reasoning: (a) A sample of potassium chloride from Chile contains the same percent by mass of potassium as one from Poland. (b) A ﬂashbulb contains magnesium and oxygen before use and magnesium oxide afterward, but its mass does not change. (c) Arsenic and oxygen form one compound that is 65.2 mass % arsenic and another that is 75.8 mass % arsenic.

A. The law of constant composition states that "all pure samples of the same chemical compound contain the same proportion of the elements by mass". Considering the pure same of KCl obtained from different locations, their samples regardless of the procedure used to make them or geography wil be in the same proportion when analysed.

B. Law of conservation of mass states that "mass can neither be created nor destroyed". This law applies to all chemical reactions in which matter is only changed from one form to another. In the bulb, magnessium and oxygen merely combines to magnessium oxide. No loss of matter.

C. Law of multiple proportion states that "when two elements combine to form two or more different compounds, the masses of one of the elements which seperately combine with a fixed mass of the other element are in a simple ratio ".