$\gamma$-decay occurs when

$A$ nucleus ${ }_{Z} X^{A}$ emits an $\alpha$-particle with velocity $v$. The recoil speed of the daughter nucleus is

Which one of the following is a possible nuclear reaction?

If a nucleus $P$ converts into a nucleus $Q$ by the decay of one alpha particle and two $\beta^{-}$ particles,then the nuclei $P$ and $Q$ are

The intensity of gamma radiation becomes $1/8$th of its initial value after traveling a distance of $36 \, mm$. After traveling what distance (in $mm$) will the intensity become half?

The atomic weight of thorium is $A = 232$ and the atomic number is $Z = 90$. After disintegration,the final element obtained is $Pb$,which has $A = 208$ and $Z = 82$. In this process,the number of emitted $\alpha$ and $\beta$ particles are: