Q. A radioactive nucleus emits $3\alpha$-particles and 5$\beta$-particles. The ratio of number of neutrons to that of protons will be
A) $\frac{A - Z - 12}{Z - 6}$
B) $\frac{A - Z}{Z - 1}$
C) $\frac{A - Z - 11}{Z - 6}$
D) $\frac{A - Z - 11}{Z - 1}$
Explanation
(d) Let
$\ _{z}X^{A}\begin{matrix}
\ \ \ \ \ \ 3\alpha\ \ \ \ \ \ \\
\longrightarrow
\end{matrix}\ _{(Z - 6)}Y\ ^{(A - 12)}{\overset{5\beta}{\rightarrow}}_{\ }{\ _{Z - 1}Y^{'}}^{(A - 12)}$
$\therefore\ \frac{No.of\ neutrons}{No.of\ protons} = \frac{A - 12 - (Z - 1)}{Z - 1} = \frac{A - Z - 11}{Z - 1}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.