The disintegration series (Thorium series) is a natural radioactive series that begins with Thorium- — Nuclear Chemistry and Radioactivity Chemistry Question

💡 Solution & Explanation

The naturally occurring disintegration series are classified based on their mass numbers. The Thorium series is the $4n$ series because the mass numbers of all its members are divisible by 4. It starts with ${}_{90}^{232}Th$ ($232 / 4 = 58$) and finishes at the stable isotope Lead-208 (${}_{82}^{208}Pb$, where $208 / 4 = 52$).