Question

A radioactive nucleus undergoes a series of decay according to the scheme $\alpha ,\beta ,\alpha ,\gamma$.
If the mass number and atomic number of '$A$' before emissions are $180$ and $72$ respectively, then what are these numbers after the emissions?

• A. $172$ and $69$
• B. $174$ and $70$
• C. $176$ and $69$
• D. $176$ and $70$

Answer 1

Answer: (A)

$172$ and $69$

${}_{72}{A}^{180}{\underset{}{\overset{\alpha }{\to }}}_{70}{A_1}^{176}{\underset{}{\overset{\beta }{\to }}}_{71}{A_2}^{176}{\underset{}{\overset{\alpha }{\to }}}_{69}{A_3}^{172}{\underset{}{\overset{\gamma }{\to }}}_{69}{A_4}^{172}$