The luminous zone of a flame:

Options

A. consists of unburnt carbon particles
B. possess maximum temperature
C. is yellow in colour
D. is the zone of complete combustion

Answer

### Step-by-Step Text Solution

1. **Understanding Flame Zones**: A flame consists of three distinct zones: the non-luminous zone, the luminous zone, and the dark zone. Each zone has different characteristics based on temperature, color, and combustion efficiency.

2. **Identifying the Luminous Zone**: The luminous zone is the brightest part of the flame. It is typically located in the middle of the flame when observing a candle flame.

3. **Temperature Characteristics**: The temperature in the luminous zone is moderately hot. This means that while it is not the hottest part of the flame, it is still capable of producing significant heat.

4. **Oxygen Supply**: In the luminous zone, there is an insufficient supply of oxygen. This lack of oxygen leads to incomplete combustion of the fuel.

5. **Color of the Luminous Zone**: The color of the luminous zone is yellow. This yellow color is primarily due to the presence of unburnt carbon particles that glow when heated.

6. **Presence of Unburnt Carbon**: Due to the insufficient oxygen supply, some carbon particles do not completely combust and remain unburnt, contributing to the yellow color of the luminous zone.

### Summary Statement
The luminous zone of a flame is the brightest part of the flame, located in the middle, with a moderately hot temperature. It has an insufficient supply of oxygen, resulting in incomplete combustion and the presence of unburnt carbon particles, which give it a yellow color.

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