What does the nuclear reaction $_z{X^A} \to {_{z + 1}}{Y^A} + {_{ - 1}}{e^0} + \bar \nu$ represent?

The intensity of gamma rays is reduced to half when they pass through a lead sheet of thickness $2.5 \, mm$. The absorption coefficient of lead is ......... $mm^{-1}$.

In the uranium radioactive series,the initial nucleus ${}^{238}_{92}U$ decays to the final nucleus ${}^{206}_{82}Pb$. In this process,the number of $\alpha$-particles and $\beta$-particles emitted are:

$U^{238}$ decays into $Th^{234}$ by the emission of an $\alpha$-particle. There follows a chain of further radioactive decays,either by $\alpha$-decay or by $\beta$-decay. Eventually,a stable nuclide is reached,and after that,no further radioactive decay is possible. Which of the following stable nuclides is the end product of the $U^{238}$ radioactive decay chain?

In which radioactive disintegration does a neutron dissociate into a proton and an electron?

Obtain the maximum kinetic energy of $\beta$-particles and the radiation frequencies of $\gamma$-decays in the decay scheme shown in the figure. You are given that:
$m(^{198}Au) = 197.968233 \; u$
$m(^{198}Hg) = 197.966760 \; u$