Calculate the octane number of gasoline fuel, which contains `25%` n - heptane and `75%` is iso - octane.

Options

A. 25
B. 50
C. 75
D. 100

Answer

To calculate the octane number of the gasoline fuel mixture containing 25% n-heptane and 75% iso-octane, we can follow these steps:

### Step 1: Understand the components of the mixture
- The mixture consists of two components:
- n-heptane (C7H16), which has an octane number of 0.
- iso-octane (2,2,4-trimethylpentane, C8H18), which has an octane number of 100.

### Step 2: Identify the percentage composition
- The fuel mixture contains:
- 25% n-heptane
- 75% iso-octane

### Step 3: Use the formula for octane number
The octane number (ON) of a fuel mixture can be calculated using the formula:

\[ \text{ON} = \left( \text{Percentage of iso-octane} \times 100 \right) + \left( \text{Percentage of n-heptane} \times 0 \right) \]

### Step 4: Substitute the values
Substituting the values into the formula:

\[ \text{ON} = (75\% \times 100) + (25\% \times 0) \]

### Step 5: Calculate the octane number
Calculating the above expression:

\[ \text{ON} = 75 + 0 = 75 \]

### Step 6: Conclusion
The octane number of the gasoline fuel mixture is **75**.

### Final Answer
The octane number of the gasoline fuel is **75**.

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