Question

Which one is true for the octane number of following organic compounds?

• A. Aromatic Compound $>$ Aliphatic compound
• B. Aromatic compound $<$ Aliphatic compound
• C. Aromatic compound $=$ Aliphatic compound
• D. None of the above

Answer 1

The correct option is A Aromatic Compound $>$ Aliphatic compound

The octane number of a fuel is based on how fuels auto-ignite, under compression.

1. It is based on the scale where isooctane is 100 (minimal ignition under pressure) and heptane is 0 (easily ignites under pressure).

For example, petrol with an octane number of 92 has the same knock as a mixture of 92% isooctane and 8% heptane.

2. Octane rating decreases with an increase in the carbon chain length.

3. Octane ratings increase with carbon chain branching.

4. Octane ratings increase in aromatics with the same number of carbons.

Hence, the correct option is $A$