Multiple choice

Unburned carbon particles are present in the ___________ zone of the flame.

  1. blue

  2. dark inner

  3. luminous

  4. non-luminous

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The luminous (yellow) zone of a flame contains unburnt carbon particles that glow due to incomplete combustion. These carbon particles are formed when hydrocarbon fuels don't fully combust due to limited oxygen supply. Option C correctly identifies the luminous zone. The blue zone (A) has complete combustion with no unburnt carbon. The dark inner zone (B) is the coolest region with unburnt fuel vapors. The non-luminous zone (D) is the blue outer zone.

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