Question

What is meant by half life of radioactive nuclide?

Answer 1

Hint: The term half-life is used to identify a decay process that can be exponential or any approximately exponential process. If a decay process is not exponential then half-life in that decay will change drastically.

Complete answer:
The half-life of a radioactive nuclide is the time taken for the radioactivity of a substance to fall half of its original value. Or it can also be defined as the interval of time taken for one-half of the atomic nuclei of the radioactive sample to decay.
 $ \lambda = \dfrac{{0.693}}{{t_{1/2}}} $ Or $ t_{1/2} = \dfrac{{0.693}}{\lambda } $
Where $ t_{1/2} $ the half-life of the radioactive sample is, $ \lambda $ is the decay constant. This relation explains that elements that are highly radioactive decay quickly decayed in contrast to elements that radiate weakly and can endure longer. In other words, the time needed to weaken radioactivity and reduce it to half is also known as half time.
 $ N = N_0{e^{ - \lambda t_{1/2}}} $
Where $ N_0 $ is the original activity and N is activity after the decay of one-half of the substances.

Note:
Half-life is the characteristic property of some unstable atomic nuclei and the particular way in which they decay. Alpha and beta decay are usually slower than gamma decay.
The Half-life for beta decay is ranged from one-hundredth of a second and, for alpha decay upward from one-millionth of a second. Where half-life for gamma decay is probably too short to measure.
Half-life is important because we can identify the long-lived and short-lived radioactive elements and also acknowledge the stability of the elements. Since the element which has a longer half-life will be present in the environment for a longer period than the element with a short half-life.