Q. A hypothetical radioactive nucleus decays according to the following series $\ _{72}A^{180}\ \ \overset{\ \ \ \ \alpha\ \ \ \ \ }{\rightarrow}A_{1}\overset{{\ \ \ \ \beta}^{-}}{\rightarrow}A_{2}\overset{\ \ \ \alpha\ \ \ \ }{\rightarrow}A_{3}\overset{\ \ \ \ \gamma\ \ \ \ }{\rightarrow}A_{4}$ If the mass number and atomic number of A are respectively 180 and72. Then to atomic number and mass number of A will respectively be
A) 69,171
B) 70,172
C) 68,172
D) 69,172
Explanation
(d) $\ _{72}A^{100}\ \overset{\ \ –\alpha\ \ \ \ \ }{\rightarrow}\ _{70}\ A_{1}^{176}\overset{\ \ \ \ - \beta\ \ \ \ }{\rightarrow}\ \ _{71}A_{2}^{176}\overset{\ \ \ - \alpha\ \ \ \ }{\rightarrow}$
$\ _{69}A_{3}^{172}\overset{\gamma\ }{\rightarrow}\ \ _{69}A_{4}^{172}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.