Question

What is meant by the terms half-life of a radioactive substance and binding energy of a nucleus?

Answer 1

half life of a radioactive substance is defined as the time by which half of the initially presented radioactive substance has decayed.
Half-life is calculated by $T_{1/2}=\frac{\ln 2}{\lambda }$
Binding energy of nucleus is defined as the minimum amount of energy required to break the nucleus into its constituent neutrons and protons.
Binding energy is calculated by $E_B=\Delta M{c}^2$
where $\Delta M$ is the mass defect of nucleus.