Question

In a series of radioactive decays, if a nucleus of mass number $180$ and atomic number $72$ decays into another nucleus of mass number $172$ and atomic number $69$, then the number of $\alpha$ and $\beta$ particles released respectively are

• A. $2,3$
• B. $2,2$
• C. $2,1$
• D. $2,0$
• E. $1,3$

Answer 1

The correct option is B $2,2$

Mass number of nucleus is decreased by $8$ and atomic number is decreased by $3$. So, the number of $\alpha -particles$ are two and number of $\beta -particles$ is one.
${}_{72}^{180}X\to \underset{(\alpha -decay)}{{}_{69}^{172}Y}+\underset{(\beta -decay)}{2\left({}_2^{4}He\right)}{+}_{-1}^{0}e$.