In the commercial gasolines, the type of hydrocarbons which are more desirable is

Options

A. Linear unsaturated hydrocarbon
B. Toulene
C. Branced hydrocarbon
D. Straight-chain hydrocarbon

Answer

To solve the question regarding the type of hydrocarbons that are more desirable in commercial gasolines, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Gasoline Composition**:
- Gasoline is primarily composed of hydrocarbons. These hydrocarbons can be classified into different types based on their structure, such as linear, branched, and cyclic hydrocarbons.

2. **Importance of Octane Number**:
- The performance of gasoline is often measured by its octane number. The octane number indicates the fuel's ability to resist knocking during combustion. A higher octane number means better performance and efficiency.

3. **Knocking in Engines**:
- Knocking occurs when fuel combusts prematurely in the engine, causing a knocking sound. This is undesirable as it can lead to engine damage. Fuels with a high octane number are less likely to knock.

4. **Types of Hydrocarbons**:
- Hydrocarbons can be linear (straight-chain) or branched. Linear hydrocarbons tend to have lower octane numbers compared to branched hydrocarbons.

5. **Comparison of Hydrocarbons**:
- For example, n-octane (a linear hydrocarbon) has an octane number of 20, while 2,2,4-trimethylpentane (a branched hydrocarbon) has an octane number of 100. This significant difference illustrates that branched hydrocarbons are much more desirable for use in gasoline.

6. **Conclusion**:
- Based on the above points, the type of hydrocarbons that are more desirable in commercial gasolines are branched hydrocarbons due to their higher octane numbers and better resistance to knocking.

### Final Answer:
The type of hydrocarbons which are more desirable in commercial gasolines is **branched hydrocarbons**.