In which radioactive disintegration, neutron dissociates into proton and electron

What is the respective number of $\alpha $ and $\beta $ particles emitted in the following radioactive decay

$_{90}{X^{200}}{ \to _{80}}{Y^{168}}$

A deutron is bombarded on $_8{O^{16}}$ nucleus and $\alpha$-particle is emitted. The product nucleus is

A radioactive nucleus undergoes $\alpha$- emission to form a stable element. What will be the recoil velocity of the daughter nucleus if $V$ is the velocity of $\alpha$-emission and $A$ is the atomic mass of radioactive nucleus

Beta rays emitted by a radioactive material are

${U^{238}}$ decays into $T{h^{234}}$ by the emission of an $\alpha - $ particle. There follows a chain of further radioactive decays, either by $\alpha - $ decay or by $\beta $ - decay. Eventually a stable nuclide is reached and after that, no further radioactive decay is possible. Which of the following stable nuclides is the and product of the ${U^{238}}$ radioactive decay chain