Question

In the uranium radioactive series, the initial nucleus is ${{}_{92}U}^{238}$ and that the final nucleus is ${{}_{82}Pb}^{206}$. When uranium nucleus decays to lead the number of $\alpha$- particles and $\beta -$ particles emitted are:

• A. $8\alpha ,6\beta$
• B. $6\alpha ,7\beta$
• C. $6\alpha ,8\beta$
• D. $4\alpha ,3\beta$

Answer 1

The correct option is A $8\alpha ,6\beta$

Let the number of $\alpha$-particles emitted be $x$ and the number of $\beta$-particles emitted be $y$.

Now, difference in mass number $=4x=238-206=32$

So, $x=8$

Now, difference in charge number $=2x-y=92-82=10$

$⟹16-y=10$

$⟹y=6$