Răspuns:
Explicație:
U²³⁸→α+Th²³⁴
Pb²⁰⁹→β+Bi²⁰⁹
Po²¹⁴→α+Pb²¹⁰→α+Pb²¹⁰→α+β+Bi²¹⁰→α+β+β+Po²¹⁰
Th²³²→α+Ra²²⁸ →α+α+Rn²²⁴→α+α+α+Po²²⁰→α+α+α+α+Pb²¹⁶→....
Th²³²₉₀ → 6α⁴₂ + 4β⁰₋₁ +Pb²⁰⁸₈₂
