Answer
See answers. There are 2 ways to tell.
Work Step by Step
There are 2 ways to tell.
a. Elemental conversion.
In internal conversion, the atom ejects an orbital electron. The atomic number of the nucleus stays the same.
In $\beta$ decay, the nucleus emits an electron while a neutron changes into a proton. The atomic number of the nucleus increases by one, and the atom is now different.
b. The continuous vs. quantized energy of the emitted electron.
In $\beta$ decay, a neutrino is emitted along with the electron, so there are three decay products. The neutrino shares the released energy with the electron, so the momentum and energy of the $\beta$ particle has a continuous range of values.
In contrast, the internal conversion process has two decay products, not three. The emitted electron has a unique energy (that depends on its starting energy level).