Question

If it is assumed that ${}_{92}^{235}U$ decays only by emitting $\alpha -$ and $\beta$-particles, the possible product of the decay is

• A. ${}_{89}^{225}Ac$
• B. ${}_{89}^{227}Ac$
• C. ${}_{89}^{230}Ac$
• D. ${}_{89}^{231}Ac$

Answer 1

The correct option is B ${}_{89}^{227}Ac$

Atomic mass (or mass number) is changed only when and $\alpha$-particle is emitted, it is not affected by the emission of $\beta$-particle.
$\therefore {}_{92}^{235}U\underrightarrow{-\alpha }{}_{90}^{231}Y\underrightarrow{-\alpha }{}_{88}^{227}X\underrightarrow{-\beta }{}_{89}^{227}Ac$