🔍 Key Concepts

• Combustion efficiency and how flame color relates to how completely the fuel is burning • How unburned fuel or soot affects flame color in furnaces or boilers • Typical color of a hot, clean-burning flame versus a smoky or sooty flame

💭 Think About

• Which flame color usually indicates the presence of soot, smoke, or unburned fuel? • Which color is typically associated with the hottest, cleanest part of a flame (like a well-adjusted gas burner)? • Among the choices, which shade suggests the least amount of orange/red (which often comes from cooler, less complete combustion)?

✅ Before You Answer

• Make sure you connect darker/redder colors with cooler, less efficient burning • Think about what flame color you’d expect from a properly adjusted gas or oil burner with minimal smoke • Eliminate any colors you associate with sooty, smoky, or lazy flames rather than sharp, hot ones