$\beta$-particle is emitted in radioactivity by

An element with atomic number $84$ and mass number $218$ loses one $\alpha$-particle and two $\beta$-particles in three successive stages. The resulting element will have:

Tritium,a radioactive isotope of hydrogen,emits which of the following particles?

Of the following radiations,the one most easily stopped by air is

Which of the following radioisotopes is used as anticancerous?

In the radioactive decay of $X$ into $Y$ as shown below,what is the value of $_Z{Y^m}$?
$_{6}{X^{14}} \xrightarrow{-3\beta} {_{Z}}{Y^{m}}$