Question

What is radioactivity? Explain half life concept. Derive the formula for half life and mean life of a radioactive material.

Answer 1

Radioactive decay is the process by which an unstable atomic nucleus loses energy by emitting radiation, such as an alpha particle, beta particle with neutrino or only a neutrino in the case of electron capture, or a gamma ray or electron in the case of internal conversion.
Half-life is defined as the amount of time it takes for half of an isotope to change into another isotope. ... This means that, like the decay constant, the half-life gives an estimate of the stability of a particular radioactive substance, and it can thus be used to identify unknown isotopes.
Radioactive Half-Life Formula. A radioactive half-life refers to the amount of time it takes for half of the original isotope to decay. For example, if the half-life of a 50.0 gram sample is 3 years, then in 3 years only 25 grams would remain.