The flame in this ____ zone is blue in colour.

Options

A. Non-luminous
B. Luminous
C. Dark zone
D. Inner dark zone

Answer

To answer the question "The flame in this ____ zone is blue in colour," we need to identify which zone of a flame exhibits a blue color.

### Step-by-Step Solution:

1. **Understand the Zones of a Flame**: A flame consists of different zones, each with distinct characteristics. The main zones are the luminous zone, non-luminous zone, dark zone, and inner dark zone.

2. **Identify the Non-Luminous Zone**: The non-luminous zone is known for its complete combustion. In this zone, there is sufficient oxygen supply, which allows for the complete burning of the fuel.

3. **Color of the Flame in the Non-Luminous Zone**: The flame in the non-luminous zone is blue in color. This blue color indicates that the combustion is efficient and complete, resulting in minimal soot production.

4. **Examine Other Zones**:
- The **Luminous Zone** has limited oxygen supply and produces a yellow flame due to incomplete combustion.
- The **Dark Zone** and **Inner Dark Zone** do not support combustion at all because there is no oxygen present, resulting in a black color.

5. **Conclusion**: Since the question specifies a blue flame, the correct answer is the non-luminous zone.

### Final Answer:
The flame in this **non-luminous** zone is blue in color.

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