Pauli suggested the emission of neutrino during $\beta^{+}$ decay to explain:

In the uranium radioactive series,the initial nucleus is $_{92}U^{238}$ and the final nucleus is $_{82}Pb^{206}$. When the uranium nucleus decays to lead,the number of $\alpha$-particles emitted is $x$ and the number of $\beta$-particles emitted is $y$. Find $x$ and $y$.

Radioactivity was discovered by

Beta rays emitted by a radioactive material are

${ }_{92} U^{235}$ undergoes successive disintegrations with the end product of ${ }_{82} Pb^{203}$. The number of $\alpha$ and $\beta$ particles emitted are

In the uranium series,the decay constant of the parent nuclide is $\lambda$. What is the decay constant of the stable end product of this series?