In which zone of a flame fuel remains in vapour form?

Options

A. blue
B. dark zone
C. luminous zone
D. non-luminous zone

Answer

To determine in which zone of a flame the fuel remains in vapor form, we can analyze the characteristics of the different zones of a flame. Here’s a step-by-step solution:

### Step 1: Understand the Zones of a Flame
A flame typically has three distinct zones: the dark zone, the luminous zone, and the non-luminous zone. Each zone has different characteristics regarding temperature and combustion.

### Step 2: Identify the Dark Zone
The dark zone, also known as the inner zone, is the area closest to the fuel source. It is characterized by a lack of visible light and is cooler compared to the other zones.

### Step 3: Analyze the Conditions in the Dark Zone
In the dark zone, there is insufficient oxygen supply for complete combustion. As a result, the fuel does not burn completely and remains in vapor form. This is why the fuel is not ignited in this zone.

### Step 4: Conclusion
Since the dark zone does not support burning due to the lack of air (oxygen), the fuel remains in vapor form in this zone.

### Answer
The fuel remains in vapor form in the **dark zone** of a flame.

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