Question

A _____reaction is a process by which atoms change their ion charge.

Answer 1

Redox: involve the transfer of electrons between two chemical species. The compound that loses an electron is said to be oxidized, the one that gains an electron is said to be reduced. There are also specific terms that describe the specific chemical species.

Substitution:A substitution reaction is a type of chemical reaction where an atom or functional group of a molecule is replaced by another atom or functional group.

Combustion: a chemical reaction chemical that occurs between a fuel and an oxidizing agent that produces energy, usually in the form of heat and light.

So it is Redox

Hope that helped :D