Who developed the study of radioactivity?

$_{11}^{23}Na$ is the more stable isotope of $Na$. Find out the process by which $_{11}^{24}Na$ can undergo radioactive decay.

The $\beta$-decay of $_{11}Na^{24}$ produces an isotope of

If a radioactive isotope with atomic number $A$ and mass number $M$ emits an $\alpha$-particle,the atomic number and mass number of that new isotope will become:

The element used for dating the ancient remains is

In the radioactive decay $_{92}X^{232} \to _{89}Y^{220}$,how many $\alpha$ and $\beta$-particles are ejected from $X$ to form $Y$?