Nuclear Physics Questions

If $M_O$ is the mass of an oxygen isotope ${}_8^{17}\text{O}$, $M_p$ and $M_n$ are the masses of a proton and a neutron respectively, the nuclear binding energy of the isotope is:

In gamma ray emission from a nucleus:

The half-life period of a radioactive element $X$ is same as the mean lifetime of another radioactive element $Y$. Initially they have the same number of atoms. Then: