the half-life of a substance is defined as the period of time it takes for the amount of the substance to decay by half. The sequence below shows the amount of the substance that will be left after a number of half lives have elapsed... 1, 1/2, 1/4, 1/8

the law of definite proportions states samples of a compound will always contain the same proportion of elements by mass. in other words, a given compound will always contain the same elements in the same proportions by mass.the law of multiple proportions states when two elements combine with each other to form more than one compound, then the weights of one element that combine with a fixed weight of the other are in a ratio of small whole numbers.