Certain radioactive nuclei decay to produce new nuclei that are themselves radioactive. A section of a decay chain is shown: $^{{238}}_{{92}}\text{U} \rightarrow ^{{234}}_{{90}}\text{Th} \rightarrow ^{{234}}_{{91}}\text{Pa} \rightarrow ^{{234}}_{{92}}\text{U} \rightarrow ^{{230}}_{{90}}\text{Th} \rightarrow ^{{226}}_{{88}}\text{Ra}$. How many of the decays include the emission of a $\beta$-particle?
- A1
- B2
- C3
- D5