What condition is found when you have a yellow flame?

What condition is found when you have a yellow flame?

• A. Complete combustion
• B. Excess air
• C. Blue flame
• D. Incomplete combustion

Answer: (D)

The color of a gas flame reflects how completely the fuel is burning. A yellow flame means incomplete combustion, because the fuel isn’t mixing with enough oxygen and unburned carbon particles (soot) glow as the flame burns. This indicates the flame is fuel-rich and not burning efficiently. Complete combustion, by contrast, produces a blue flame, signaling proper air-fuel mix. Excess air tends to push the flame toward blue as well, not yellow. So the yellow flame points to incomplete combustion.

The color of a gas flame reflects how completely the fuel is burning. A yellow flame means incomplete combustion, because the fuel isn’t mixing with enough oxygen and unburned carbon particles (soot) glow as the flame burns. This indicates the flame is fuel-rich and not burning efficiently. Complete combustion, by contrast, produces a blue flame, signaling proper air-fuel mix. Excess air tends to push the flame toward blue as well, not yellow. So the yellow flame points to incomplete combustion.