What type of gas is methane?

Methane is classified as a flammable gas, which is the correct answer. It is the simplest hydrocarbon and is highly combustible, meaning it can easily ignite and burn when mixed with air. This property is due to the presence of carbon and hydrogen in its molecular structure, allowing it to react with oxygen and release energy in the form of heat and light.

The flammability of methane is an important consideration in wastewater treatment facilities and other industrial processes where methane might be produced, such as in anaerobic digestion. Facilities need to have proper safety measures in place to handle and prevent accidental ignitions of methane.

In contrast, other gas types mentioned in the options, such as inert gases and noble gases, do not combust and are generally non-reactive. Toxic gases are harmful to living organisms, but methane is not classified this way under normal conditions, making the identification of methane as a flammable gas the most appropriate classification.