Question

Two identical nuclei $A$ and $B$ of the same radioactive element undrego $\beta$ decay. A emits a $\beta$ -particles and changes to $A{}^{\prime }$. $B$ emits a $\beta$ -particle and then a $\gamma$ -ray photon immediately afterwards, and changes to $B{}^{\prime }$

• A. $A{}^{\prime }$ and $B{}^{\prime }$ have the same atomic number and mass number
• B. $A{}^{\prime }$ and $B{}^{\prime }$ have the same atomic number but different mass numbers
• C. $A{}^{\prime }$ and $B{}^{\prime }$ have different atomic number but the same mass number
• D. $A{}^{\prime }$ and $B{}^{\prime }$ are isotops

Answer 1

The correct option is A $A{}^{\prime }$ and $B{}^{\prime }$ have the same atomic number and mass number

For $\beta$ decay , atomic number $Z$ will increase by $1$ unit and mass number A will not change. For $\gamma$ , nucleus will get excited and no change of Z and A.
Thus, the nuclei A' and B' have same atomic number $(Z+1)$ and same mass number A.