Conditions when Ionization occurs

Question

What are the conditions when Ionization takes place?

Answer 1

i) Whenever atoms lose electrons; they become scarce in negative charges and thus behave as positively charged atoms.

ii) Whenever atoms gain electrons; they will be positively charged.

iii) Whenever an atom loses its nucleus.

iv) Only whenever K-orbit electron is ejected and substituted by an L-orbit.