A neptunium-236 nucleus contains $93$ protons and $143$ neutrons. It undergoes decay by releasing an $\alpha$-particle. The nucleus produced then emits a $\beta^{-}$ particle. Which diagram indicates the changes in the number $P$ of protons and the number $N$ of neutrons in these nuclei?
Physics 9702 · AS & A Level · Atoms, nuclei and radiation