The element used for dating the ancient remains is

After losing a number of $\alpha$ and $\beta$ particles,$_{92}U^{238}$ changed to $_{82}Pb^{206}$. The total number of particles lost in this process is

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

The radiations having high penetrating power and not affected by electrical and magnetic field are

The disintegration of an isotope of sodium,$_{11}Na^{24} \to _{12}Mg^{24} + _{-1}e^0$,shown is due to

Who developed the study of radioactivity?