Two identical nuclei `A` and `B` of the same radioactive element undergo `beta^(-)` decay. `A` emits a `beta^(-)` particle and changes to `A'`. `B` emits a `beta^(-)` particle and then a `gamma`-photon immediately afterwards, and changes to `B`.

Options

A. `A'` and `B'` have the same atomic number and mass number
B. `A'` and `B'` have the same atomic number and different mass numbers
C. `A'` and `B'` have different atomic numbers but the same mass number
D. `A'` and `B'` are isotopes

Answer

A