A fuel has the same knocking property as a mixture of 70% isooctane (2,2,-4 trimethyl pentane) and 30% n heptane by volume, the octane number of the fuel is

Answer

To determine the octane number of the fuel that has the same knocking property as a mixture of 70% isooctane and 30% n-heptane, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Octane Number**: The octane number is a measure of a fuel's ability to resist knocking during combustion. It is defined as the percentage of isooctane (which has an octane number of 100) in a mixture of isooctane and n-heptane (which has an octane number of 0).

2. **Identify the Components**: In the given mixture, we have:
- Isooctane: 70% by volume
- N-heptane: 30% by volume

3. **Calculate the Octane Number**: The octane number of a fuel mixture can be calculated using the formula:
\[ \text{Octane Number} = \left( \text{Percentage of Isooctane} \times 1 \right) + \left( \text{Percentage of N-heptane} \times 0 \right) \]
Substituting the values:
\[ \text{Octane Number} = (70\% \times 1) + (30\% \times 0) = 70 + 0 = 70 \]

4. **Conclusion**: The octane number of the fuel is therefore 70.

### Final Answer:
The octane number of the fuel is **70**.

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