Which of the following has the higest knocking property ?

Options

A. (a) Olefins
B. (b) Straight-chain paraffins
C. (c) Branched-chain paraffins
D. (d) Aromatic hydrocarbons

Explanation

To determine which of the given options has the highest knocking property, we need to understand the concept of knocking in fuels and the trends associated with different types of hydrocarbons.

### Step-by-Step Solution:

1. **Understand Knocking**:
- Knocking refers to the metallic sound produced due to the irregular combustion of fuel in an engine. It is an undesirable phenomenon as it indicates inefficient combustion and energy loss.

2. **Identify the Ideal Fuel**:
- An ideal fuel is one that minimizes knocking. Therefore, fuels with lower knocking tendencies are preferred for efficient combustion.

3. **Analyze the Knocking Tendency**:
- The tendency of knocking varies among different types of hydrocarbons. The general order of knocking tendency is as follows:
- **Straight Chain Alkanes (Unbranched)**: Highest knocking tendency.
- **Branched Alkanes**: Lower knocking tendency than straight-chain alkanes.
- **Alkenes**: Lower knocking tendency than branched alkanes.
- **Cycloalkanes**: Lower knocking tendency than alkenes.
- **Aromatic Compounds**: Lowest knocking tendency.

4. **Determine the Correct Option**:
- Based on the above analysis, if we are given a list of hydrocarbons, we should identify the straight-chain alkanes first, as they exhibit the highest knocking property.

5. **Conclusion**:
- Therefore, the correct answer to the question regarding which hydrocarbon has the highest knocking property is the straight-chain alkane.