Q 12-13-022NEETJEE MainEasy
In beta-minus decay, a nucleus emits an electron. The electron comes from
Answer: (A) a neutron changing into a proton inside the nucleus
Concept. In $\beta^-$ decay, $n \to p + e^- + \bar\nu$ inside the nucleus.
Step 1. Origin of the electron. There are no electrons inside a nucleus; the electron is created when a neutron turns into a proton. So $Z$ rises by $1$ and $A$ is unchanged.
Answer. A neutron changing into a proton inside the nucleus (Option A).
Solution by Sreeraj P, M.Sc Physics