When a nucleus emits a beta minus particle, its atomic number
- A. decreases by 1
- B. increases by 1, while the mass number is unchanged
- C. decreases by 2
- D. is unchanged
Explanation
A neutron converts into a proton, an electron and an antineutrino, so the nucleus gains a proton while the total nucleon count stays the same, moving the element one place forward in the periodic table. The emitted electron comes from the nucleus, not from the electron shells. Gamma emission, by contrast, changes neither number.