Chemistry

Problem

Calculate the group of elements formed in the final stage of radioactive changes given below: (a)

{}_{92}\text{U}^{235} \xrightarrow{-\alpha} {}_{90}\text{Th}^{231}

(b)

{}_{90}\text{Th}^{231} \xrightarrow{-\beta} {}_{91}\text{X}^{231}

(c)

{}_{91}\text{X}^{231} \xrightarrow{-\alpha} {}_{89}\text{Ac}^{227}

(d)

{}_{90}\text{Th}^{231} \xrightarrow{-\alpha} {}_{88}\text{Ra}^{227}