Answer:
4s2
Step-by-step explanation:
The electronic configuration of zinc in the ground state of the atom is 1s22s22p6 3s23p63d104s2. It can be written in a condensed form by showing the inert gas core as follows; [Ar] 3d¹⁰ 4s².
Zinc has a pseudo inert gas configuration when the 4s electrons are removed during oxidation. Hence this sublevel is usually affected when zinc atoms are oxidized according to the scheme;
Zn---->Zn^2+ + 2e-