Question

A fuel has the same knocking property as a mixture of 70% iso-octane (2, 2, 4-trimethylpentane) and 30% n-heptane by volume. The octane number of the fuel is:

• A. 100
• B. 70
• C. 50
• D. 40

Answer 1

The correct option is B 70

Octane number is defined as the percentage of iso-octane (by volume) in a mixture of iso-octane and n-heptane which has the same anti-knocking properties as the fuel under consideration.
Thus, the octane number of the given fuel is 70 as it contains 70% iso-octane.