Re: Which state of matter would fire go under?

Matter is ordinarily classified as Solid, Liquid or Gas.  Under this old 
system the flames of a fire would be classified as a gas, the products of 
combustion like carbon dioxide and water vapor.

Nowadays we also name other states of matter besides the original three, 
for instance Plasma is often called the 4th state of matter, which would 
be a better description of the flames.  Inside the flame the combustion 
reactions in the gas mixture is not complete, there are atoms and 
molecules of gas that have missing electrons.  These "ionized" gas 
molecules have received energy from the combustion which electron bonds 
between atoms are torn apart and new bonds are formed.  During this 
process they emit excess energy as light and heat.  Until the new bonds 
are complete the products in the flame are more properly called a "Plasma".

During my life science has discovered even more strange forms of matter we 
dont experience in everyday life, like Bose-Einstein Condensates "the 
coldest matter in the universe" where a group of gas atoms act together 
like a crystal, or extreme stars where ordinary atoms have been crushed 
into pure Neutrons.  Someone of your generation will likely discover still 
stranger forms of matter!