Petroleum is refined by:

Options

A. fractional distillation
B. destructive distillation
C. distillation
D. all of these

Answer

To answer the question "Petroleum is refined by:", we will analyze the process of refining petroleum and identify the correct method used for this purpose.

### Step-by-Step Solution:

1. **Understanding Refining of Petroleum**:
- Petroleum is a complex mixture of hydrocarbons and other organic compounds. To utilize these components effectively, petroleum needs to be refined.

2. **Identifying the Refining Process**:
- The primary method used for refining petroleum is **fractional distillation**. This process separates the various components of petroleum based on their boiling points.

3. **What is Fractional Distillation?**:
- Fractional distillation is a technique where a mixture is heated to vaporize its components. As the mixture is heated, different fractions of the mixture vaporize at different temperatures due to their varying boiling points.

4. **Separation of Fractions**:
- During fractional distillation, the vaporized components rise through a column and cool down at different heights, where they condense back into liquid form. Each fraction corresponds to a specific range of boiling points:
- Below 30 °C: Gases
- 30 °C to 170 °C: Gasoline
- 170 °C to 250 °C: Kerosene
- 250 °C to 350 °C: Diesel oil
- Above 350 °C: Residuum (heavy oils)

5. **Conclusion**:
- Therefore, the correct answer to the question is that petroleum is refined by **fractional distillation**.

### Final Answer:
**Petroleum is refined by fractional distillation.**

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