Which organ belongs in the circulatory system

It is both a combustion reaction and a reduction reaction

Explanation:

Let us look closely at what a combustion reaction is. A combustion reaction is a reaction in which a substance combines with oxygen to produce heat and light. The process is exothermic.

We can see that the combination of zinc and oxygen above produced heat and light hence the process is a combustion reaction according to definition.

The bone of contention however is whether it is also a reduction reaction.

Now consider the changes in oxidation number from left to right.

Zn - 0 to +2

O - 0 to -2

We can see that Zn was oxidized and O was reduced. The process is also a reduction reaction since O experienced a negative change in oxidation number.

Be reminded that oxidation and reduction processes are always simultaneous.