Calculate the average atomic mass of an element from isotope data, Example: Element Y has two isotopes. One has a mass number of 10 and a relative
abundance of 20%. The other isotope has a mass number of 11 and a relative
abundance of 80%.

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This law states that, despite chemical reactions or physical transformations,
mass is conserved, that is, it cannot be created or destroyed. within an isolated system. In other words, in a chemical reaction, the mass of the products will always be equal to the mass of the reactants.