When an atomic nucleus emits an alpha particle it decay into an atom with atomic number 2 less and mass number 4 less. Thus Thorium 230 decay as follows.
230 90Th -------> 226 88Th + 4 2 He
thorium is in the atomic number 90 thus it during alpha decay it reduces to atomic number 88 while its 230 mass number reduces to 226
The chains of volcanic islands can be found mostly alongside the borders of the convergent plate boundaries, more specifically, on the convergent boundaries between an oceanic and continental tectonic plates. That can easily be seen by the so called ''Ring of Fire'' where there's numerous chains of volcanic islands
The blank is - <span>Endoplasmic reticulum</span>
When an entire species perishes the species becomes extinct.
