A radioactive nuclide emits a β-particle. The atomic number (proton number) of the nucleus number of ______?

Stays the same

Decreases by 2

Increases by 1

Decreases by 4

When a radioactive nuclide emits a beta (β) particle, it undergoes beta decay.

In beta decay, a neutron in the nucleus is converted into a proton and an electron (the beta particle).

As a result, the atomic number (proton number) of the nucleus increases by 1.