Is a FLAME a SOLID, LIQUID, OR A GAS?
None of these. A hot enough flame with ionized parts can be considered a plasma. A flame is the part of a fire we see and feel. Neither of these is a material but what produces them is, and therefore is a in a particular state of matter while the flame exists. For a fire to be produced we need heat, oxygen and a fuel. When these three things are combined, a chemical reaction takes place, which produces new compounds. In the case of wood we get charcoal, and a gas made of carbon, hydrogen and oxygen.
As this gas is heated it breaks down and forms new substances in the form of water, carbon dioxide, and other products. The flame produced by these gases releases energy in the form of light and heat, hence a flame. To prove these substances are a gas, scientists analyze the light from the flame using spectroscopy, which will show what elements are present.