1. Fire is neither a gas nor a solid in itself. It is a chemical process which turns one material into another. The fuel can be solid (coal), liquid (gasoline), or gas (methane), and the results are often gas (usually carbon dioxide).

2. Fire needs 3 things: fuel, oxygen (or an oxidizer), and heat or spark. Again, fire is a chemical reaction between oxygen (or an oxidizer) and the fuel. Using pure oxygen instead of air allows the chemical reaction to go faster because each molecule of fuel has more chances to interact with a molecule of oxygen. It's like having more available dance partners. Removing the oxygen stops the chemical reaction.

When we have some source of carbon (say a lump of sugar sucrose,) and some oxygen (the air we breathe is 21% oxygen) then a combustion reaction occurs. This reaction can be written:

This is called a combustion reaction the products of the reaction are water and carbon dioxide. now when some sugar (or a lump of coal) burns, the gases given of, CO₂ and steam are hot...very hot and small impurities in the substance burning give a color to the flame...so the flame is simply the hot gases derived from the combustion process. So fire per se is just the term we use for the visualization of those hot gases.Without diatomic oxygen written O₂ where the two should be a SUBSCRIPT there could be no combustion reaction. Actually the combustion reaction is a type of OXIDATION reaction. In the case of burning, the carbon goes from a reduced state to an oxidized state (as CO₂).

Another burning (oxidation reaction is...RUST!!! in that reaction native metal Fe combines with oxygen to make hematite or rust
2 Fe +3/2 O₂= Fe₂O₃

So we can say that formation of blood red rust is simply the 'burning' of iron!!!

I hope this answers your question Chemistry is a very important area of study... the drugs that may some day cure cancer, the supplies you use to make buildings and computers and even the evolution of the planet earth are all examples of chemical processes. Chemistry is really fun stuff. I got interested in it when I was a kid because I used to make and fly model rockets and we used to make our own rocket fuel.

1. There are lots of states of matter besides gases and solids and liquids. Fire isn't a solid. Fire burns fuels to make gases. The fuels are mostly solids or liquids, or gases that are different from the gases that are produced by the fire. Sometimes the fire can't, or doesn't, burn up the fuel completely. Then there are things such as ashes or charcoal after the fire is done.

2. Oxygen combines with the chemicals in the fuel to make new chemicals that have oxygen in them. When that happens really fast, it is a fire. Sometimes oxygen combines slowly with chemicals, and there is no fire. Two processes I can think of where oxygen combines slowly are: 1, iron, when it rusts, and
2, fats and oils, when they get rancid.

3. The oxygen reacts chemically with the fuel when there is a fire. Other things can be happening, too. For example, wind can spread burning things to other places. Most of the forces that are big enough to measure would all be from things such as wind and not from the actual reaction of oxygen with fuel. However, fire makes heat, and heat can exert forces on things. Have you ever seen angel chimes that ring when you put them above a candle? The heat from the candle pushes on a little 'pinwheel' at the top of the angel chimes. The pinwheel moves around and around when the heat pushes on it, and the angels go around on the pinwheel, and little metal rods hanging from the angels hit the sides of little bells.

1. Fire is a chemical reaction, not a substance. Therefore it cannot be either a solid or a gas. The chemicals that are reacting usually consist of oxygen (which is a gas), and one or more forms of fuel, which can be solid, liquid, or they can also be gases.

2. Oxygen combines with other elements to form compounds that are in a more favorable, lower energy state, than the raw elements themselves. The energy lost from going from a high energy state to a low energy state has to go somewhere, and so becomes heat.

3. Any chemical reaction, including fire, requires a certain amount of heat in order to proceed. What makes fire different from many other chemical reactions is that the fire itself generates the heat necessary to cause the reaction to continue occurring, and by heating up neighboring substances, can raise them to the temperatures where they start to burn as well. Of course, in order for fire to happen, all of the ingredients need to be present: Fuel will nor burn without oxygen, and likewise oxygen cannot burn by itself either, even if the needed heat is present.