Here's why:

* States of matter (solid, liquid, gas, plasma) describe the physical arrangement of molecules.

* Fire is a process where fuel reacts with oxygen, producing heat and light.

While fire appears to have a shape and volume, it's actually a plasma - a state of matter where atoms have been stripped of their electrons. This plasma is generated by the intense heat of the combustion reaction.

So, fire is a process, not a state of matter, but it involves the creation of plasma.