Which one item of the list below does not describe part of beta decay? A. The nucleus of the atom is unstable.
B. A neutron turns into a proton.
C. A proton turns into an electron.
D. An electron is ejected from the nucleus.

C

Explanation:

When Beta decay happens, the atomic number of an element goes up, and that means there is an extra proton. A is not the answer because unstable atoms cause decay. B is also not correct because this is what happens in Beta decay: a neutron becomes a proton. D is not correct because an electron is actually emitted from the nucleus.