Answer:
Combustion and single replacement.
Step-by-step explanation:
The oxidation reduction reactions are called redox reaction. These reactions are take place by gaining or losing the electrons and oxidation state of elements are changed.
Oxidation:
Oxidation involve the removal of electrons and oxidation state of atom of an element is increased.
Reduction:
Reduction involve the gain of electron and oxidation number is decreased.
The combustion and single replacement reactions are always redox.
Consider the following reactions.
Mg + CuSO₄ → Cu + MgSO₄
the oxidation state of copper is changed from +2 to 0 so copper get reduced.
the oxidation state of Mg is changed from 0 to +2 so it get oxidized.