$\beta$-decay means emission of electron from

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?

In a radioactive reaction $_{92}X^{232} \to _{82}Y^{204}$,the number of $\alpha$-particles emitted is:

$A$ certain radioactive material can undergo three different types of decay,each with a different decay constant $\lambda_1$,$\lambda_2$,and $\lambda_3$. Then the effective decay constant is:

${ }_{82}^{290} X \xrightarrow{\alpha} Y \xrightarrow{e^{+}} Z \xrightarrow{\beta^{-}} P \xrightarrow{e^{-}} Q$
In the nuclear emission stated above, the mass number and atomic number of the product $Q$ respectively, are

$A$ nucleus with mass number $220$ initially at rest emits an $\alpha$-particle. If the $Q$ value of the reaction is $5.5\, MeV$,calculate the kinetic energy of the $\alpha$-particle in $MeV$.