Why does fire need oxygen?

Answer: Oxygen molecules react with the fuel and release energy as heat and light

Oxygen acts as the fuel that gets burned up in the fire — Wrong. Oxygen is not the fuel - it's the oxidizer. The fuel is what burns (wood, gasoline, etc.). Oxygen reacts with the fuel in a chemical reaction. Fire needs three things: fuel, oxygen, and heat (the fire triangle).

Oxygen molecules react with the fuel and release energy as heat and light ✓ — Correct! Fire is a rapid oxidation reaction. Fuel molecules react with oxygen, breaking chemical bonds and forming new ones (like CO2 and H2O), releasing energy as heat and light. Without oxygen, this reaction can't occur. That's why smothering a fire with a blanket works - you cut off the oxygen supply!

Oxygen makes the flames glow brightly so they can be seen — Wrong. Flames are visible because of glowing hot particles and excited molecules, not because of oxygen. Flames can actually occur in different colors depending on what's burning and at what temperature, but oxygen is needed for the chemical reaction, not visibility.