The appreciable radioactivity of uranium minerals is mainly due to

Tritium undergoes radioactive decay giving

During a $\beta$-decay,the mass of the atomic nucleus

$A$ radioactive nuclide $X$ decays at the rate of $1.00 \times 10^5 \ disintegration \ s^{-1} \ g^{-1}$. Radium decays at the rate of $3.70 \times 10^{10} \ disintegration \ s^{-1} \ g^{-1}$. The activity of $X$ in millicuries $g^{-1}$ $(mCi \ g^{-1})$ is

Who developed the study of radioactivity?

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