Which phase of matter is known to be capable of burning?

When discussing the phases of matter in relation to combustion, it is essential to understand that combustion typically occurs in a gaseous state. Gases are made up of molecules that are free to move independently, which allows them to disperse and mix with oxygen, a key component for combustion. When gases reach a certain temperature, they can ignite and sustain a flame, making them the phase of matter most capable of burning.

While solids and liquids can also burn, they must first undergo a process called pyrolysis (for solids) or vaporization (for liquids) to produce gases that can ignite. This means that, although solids and liquids can contribute to combustion, they primarily do so by transforming into gases that then participate in the burning process. Plasma, on the other hand, is a state of matter where gas is ionized and can conduct electricity; it does not burn in the traditional sense that we consider with fires.

Thus, gases are inherently capable of combustion without needing to transform into another phase, making them the most direct answer concerning burning.