The integrated form of the first-order rate law of nuclear decay is expressed as follows. - At = in N () In this equation, 2 is the decay constant, t is time, N is the number of nuclei remaining at time t, and N. is the original number of nuclei present. How much time will a radioactive element require to reduce its activity to exactly five-sixths of its initial activity, if its decay constant i = 3.5638x10-2 8-17 d