Who discovered the meson?

In a fission reaction,the nucleus of an element:

In the successive emission of $\alpha$- and $\beta$-particles,the number of $\alpha$- and $\beta$-particles that should be emitted for the conversion of ${}^{238}_{92}U$ to ${}^{206}_{82}Pb$ are:

$A$ possible material for use in nuclear reactors as a fuel is

When a slow neutron goes sufficiently close to a ${^{235}U}$ nucleus,then the process which takes place is

If ${}^{235}U$ is bombarded with neutrons,the atom will split into: