A radioactive nuclide of atomic number Z emits an alpha part

A radioactive nuclide of atomic number Z emits an alpha particle and the daughter nucleus thern A radioactive nuclide of atomic number Z emits an alpha particle and the daughter nucleus then emits a beta particle. What is the atomic number of the resulting nuclide? A) Z-1 B) Z+1 C) Z-2 D) Z-3

Solution

When a radioactive nucleus emits an alpha particle, its atomic number changes from Z to Z-2 and mass number changes from A to A-4. Then if it emits a beta particle, its mass number remains unchanged at A-4 but its atomic number increases by 1 to become Z-1.

A) Z-1