Which waves are used in the treatment of cancer?

In the following nuclear reaction,$x$ stands for: $n \rightarrow p + e^{-} + x$

An atomic nucleus $_{90}Th^{232}$ emits several $\alpha$ and $\beta$-radiations and finally reduces to $_{82}Pb^{208}$. It must have emitted:

The intensity of gamma radiation emitted from a source is $I_0$. After passing through a lead sheet of thickness $36 \, mm$,its intensity becomes $I_0/8$. Find the thickness of the lead sheet in $mm$ when the intensity becomes $I_0/2$.

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

Which of the following is not a mode of radioactive decay?