Chemical reactions must be balanced due to Select an answer the law of multiple proportions the law of conservation of mass the law of definite composition the law of definite proportions which states Select an answer chemical reactions must always be balanced with whole numbers when two elements combine to form more than one compound, the mass of one element combined with a fixed mass of the other element, will always be ratios of whole numbers matter cannot be created or destroyed a given chemical compound always contains its component elements in fixed ratio .