The quality of petrol is expressed in term of :Select an answerAOctane numberBDecane numberCCetane numberDQuantum number

Break Down the Problem

1. Understand the terms related to the quality of petrol.
2. Identify which of the provided options is specifically related to petrol quality.

Relevant Concepts

1. Octane Number: Indicates the fuel's ability to resist knocking during combustion.
2. Decane Number: Less commonly referenced, related to the performance of fuels similar to octane.
3. Cetane Number: Related to diesel fuels, not petrol.
4. Quantum Number: Pertains to quantum mechanics, not relevant to fuel quality.

Analysis and Detail

1. The octane number is the most commonly used measure for petrol (gasoline) quality. It reflects how well the fuel can withstand compression in an engine before igniting (knocking).
2. Cetane number, on the other hand, measures the ignition quality of diesel fuel, thus irrelevant in this context.

Verify and Summarize

• Among the options provided, the Octane number is the standard measure for petrol quality.

Final Answer

A - Octane number is the correct answer.