The law about radioactive decay is a universal law, and it is used for describing the statistical behavior of a large number of nucleoids. The radioactive decay is not a regular process but a random one. It occurs at the level of single atoms, and according to the quantum theory, the prediction about the decay of a particular atom is not possible. In other words, it can be said that the nucleus of radionuclide is not having any memory. With time, the nucleus is not getting aged. So, with the time, the probability of its breaking is not increased. But despite its life span, it will stay constant. During this unpredicted decay, the unstable nucleus is randomly and spontaneously decomposed to make different nucleus. In this process, the radiation is given off in terms of high energy rays or atomic particles.

Relatively, the calculations of radioactive decay of nuclei are straightforward. It is owed to the fact that only one fundamental law is governing all kinds of decay processes. The law of radioactive decay states that probability per unit time, for decaying of the nucleus, remains constant, and it is not dependent on time. This constant is known as the decay constant and is denoted by the lambda. The probability of the constant greatly varies between different kinds of nuclei that lead to the observation of different decay rates.

Radioactive decay law: N = N.e-λt