Name a few examples of flammable gases.

Flammable gases are substances that can easily ignite and sustain combustion when mixed with air or oxygen. The correct answer includes propane, butane, and hydrogen, all of which are recognized for their flammability.

Propane is commonly used as a fuel for heating appliances, cooking, and vehicles. It has a specific range of concentrations in air that can ignite, making it a serious hazard if not handled properly. Butane, similar to propane, is primarily used as a fuel and is also flammable with a low ignition point, making it dangerous in enclosed spaces. Hydrogen, the simplest and most abundant element, is highly flammable and can ignite easily, leading to explosive reactions when mixed with air.

In contrast, the other choices do not include substances typically classified as flammable gases. Oxygen, carbon dioxide, and helium are non-flammable; they do not combust under normal conditions. Argon, nitrogen, and neon are inert gases, meaning they do not easily react or ignite. Lastly, while acetylene is flammable, ammonia and sulfur dioxide are typically considered toxic rather than flammable gases, which makes the combination in that choice less representative of flammable gases overall.